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Sample records for 10-12 hz frequency

  1. Electrophysiological signatures of intentional social coordination in the 10-12 Hz range.

    PubMed

    Naeem, Muhammad; Prasad, Girijesh; Watson, David R; Kelso, J A Scott

    2012-01-16

    This study sought to investigate the effects of manipulating social coordination on brain synchronization/de-synchronization in the mu band. Mu activation is associated with understanding and coordinating motor acts and may play a key role in mediating social interaction. Members of a dyad were required to interact with one another in a rhythmic finger movement coordination task under various instructions: intrinsic where each member of the dyad was instructed to maintain their own and ignore their partner's movement; in-phase where they were asked to synchronize with their partner's movement; and anti-phase where they were instructed to syncopate with their partner's movement. EEG and movement data were recorded simultaneously from both subjects during all three tasks and a control condition. Log power ratios of EEG activity in the active conditions versus control were used to assess the effect of task context on synchronization/de-synchronization in the mu spectral domain. Results showed clear and systematic modulation of mu band activity in the 10-12 Hz range as a function of coordination context. In the left hemisphere general levels of alpha-mu suppression increased progressively as one moved from intrinsic through in-phase to anti-phase contexts but with no specific central-parietal focus. In contrast the right hemisphere displayed context-specific changes in the central-parietal region. The intrinsic condition showed a right synchronization which disappeared with the in-phase context even as de-synchronization remained greater in the left hemisphere. Anti-phase was associated with larger mu suppression in the right in comparison with left at central-parietal region. Such asymmetrical changes were highly correlated with changing behavioral dynamics. These specific patterns of activation and deactivation of mu activity suggest that localized neural circuitry in right central-parietal regions mediates how individuals interpret the movements of others in the

  2. 78 FR 42102 - Termination of Radiotelephone Medium Frequency 2182 kHz Watchkeeping, 2187.5 kHz Digital...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-15

    ... SECURITY Coast Guard Termination of Radiotelephone Medium Frequency 2182 kHz Watchkeeping, 2187.5 kHz Digital Selective Calling Channel Guard, and 2670 kHz Broadcasts ACTION: Notice. SUMMARY: The United States Coast Guard is announcing that it will no longer maintain a watch on 2182 kHz, will no...

  3. The 10 Hz Frequency: A Fulcrum For Transitional Brain States

    PubMed Central

    Garcia-Rill, E.; D’Onofrio, S.; Luster, B.; Mahaffey, S.; Urbano, F. J.; Phillips, C.

    2016-01-01

    A 10 Hz rhythm is present in the occipital cortex when the eyes are closed (alpha waves), in the precentral cortex at rest (mu rhythm), in the superior and middle temporal lobe (tau rhythm), in the inferior olive (projection to cerebellar cortex), and in physiological tremor (underlying all voluntary movement). These are all considered resting rhythms in the waking brain which are “replaced” by higher frequency activity with sensorimotor stimulation. That is, the 10 Hz frequency fulcrum is replaced on the one hand by lower frequencies during sleep, or on the other hand by higher frequencies during volition and cognition. The 10 Hz frequency fulcrum is proposed as the natural frequency of the brain during quiet waking, but is replaced by higher frequencies capable of permitting more complex functions, or by lower frequencies during sleep and inactivity. At the center of the transition shifts to and from the resting rhythm is the reticular activating system, a phylogenetically preserved area of the brain essential for preconscious awareness. PMID:27547831

  4. 47 CFR 90.253 - Use of frequency 5167.5 kHz.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Use of frequency 5167.5 kHz. 90.253 Section 90.253 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES... frequency 5167.5 kHz. The frequency 5167.5 kHz may be used by any station authorized under this part...

  5. 47 CFR 90.253 - Use of frequency 5167.5 kHz.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Use of frequency 5167.5 kHz. 90.253 Section 90.253 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES... frequency 5167.5 kHz. The frequency 5167.5 kHz may be used by any station authorized under this part...

  6. 47 CFR 90.253 - Use of frequency 5167.5 kHz.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Use of frequency 5167.5 kHz. 90.253 Section 90.253 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES... frequency 5167.5 kHz. The frequency 5167.5 kHz may be used by any station authorized under this part...

  7. 47 CFR 90.253 - Use of frequency 5167.5 kHz.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Use of frequency 5167.5 kHz. 90.253 Section 90.253 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES... frequency 5167.5 kHz. The frequency 5167.5 kHz may be used by any station authorized under this part...

  8. 47 CFR 90.253 - Use of frequency 5167.5 kHz.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Use of frequency 5167.5 kHz. 90.253 Section 90.253 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES... frequency 5167.5 kHz. The frequency 5167.5 kHz may be used by any station authorized under this part...

  9. Free-field calibration of measurement microphones at frequencies up to 80 kHz

    NASA Astrophysics Data System (ADS)

    Zuckerwar, Allan J.; Herring, Gregory C.

    2002-11-01

    Civil-aviation noise-reduction programs, that make use of scaled-down aircraft models in wind tunnel tests, require knowledge of microphone pressure (i.e., not free-field) sensitivities beyond 20 kHz--since noise wavelengths also scale down with decreasing model size. Furthermore, not all microphone types (e.g., electrets) are easily calibrated with the electrostatic technique, while enclosed cavity calibrations typically have an upper limit for the useful frequency range. Thus, work was initiated to perform a high-frequency pressure calibration of Panasonic electret microphones using a substitution free-field method in a small anechoic chamber. First, a standard variable-frequency pistonphone was used to obtain the pressure calibration up to 16 kHz. Above 16 kHz, to avoid spatially irregular sound fields due to dephasing of loudspeaker diaphragms, a series of resonant ceramic piezoelectric crystals was used at five specific ultrasonic frequencies as the free-field calibration sound source. Then, the free-field sensitivity was converted to a pressure sensitivity with an electrostatic calibration of the reference microphone (an air condenser type), for which the free-field correction is known. Combining the low- and high-frequency data sets, a full frequency calibration of pressure sensitivity for an electret microphone was generated from 63 Hz to 80 kHz.

  10. Calibration of laser vibrometers at frequencies up to 100 kHz and higher

    NASA Astrophysics Data System (ADS)

    Silva Pineda, Guillermo; von Martens, Hans-Jürgen; Rojas, Sergio; Ruiz, Arturo; Muñiz, Lorenzo

    2008-06-01

    Manufacturers and users of laser vibrometers exploit the wide frequency and intensity ranges of laser techniques, ranging over many decades (e.g., from 0.1 Hz to 100 MHz). Traceability to primary measurement standards is demanded over the specified measurement ranges of any measurement instrumentation. As the primary documentary standard ISO 16063-11 for the calibration of vibration transducers is restricted to 10 kHz, a new international standard for the calibration of laser vibrometers, ISO 16063-41, is under development. The current stage of the 2nd Committee Draft (CD) of the ISO standard specifies calibration methods for frequencies from 0.4 Hz to 50 kHz which does not meet the demand for providing traceability at higher frequencies. New investigations will be presented which demonstrate the applicability of the laser interferometer methods specified in ISO 16063-11 and in the 2nd CD also at higher frequencies of 100 kHz and beyond. The three standard methods were simultaneously used for vibration displacement and acceleration measurements up to 100 kHz, and a fourth high-accuracy method has been developed and used. Their results in displacement and acceleration measurements deviated by less than 1 % from each other at vibration displacement amplitudes in the order of 100 nm. In addition to the three interferometer methods specified in ISO 16063-11 and 16063-15, and in the 2nd Committee Draft of 16063-41 as well, measurement results will be presented. Examples of laser vibrometer calibrations will bedemonstrated. Further investigations are aimed

  11. Dependence of kHz quasi-periodic oscillation frequencies on accretion-related parameters

    NASA Astrophysics Data System (ADS)

    Erkut, M. Hakan; Catmabacak, Onur; Duran, Sivan; Çatmabacak, Önder

    2016-07-01

    To study the possible dependence of kHz QPO frequencies on the parameters such as the mass accretion rate, the surface magnetic field strength, mass, and radius of the neutron star, we consider the up-to-date distribution of neutron star LMXBs in the kHz QPO frequency versus X-ray luminosity plane. We confirm the absence of any correlation between QPO frequencies and luminosity in the ensemble of LMXBs. Searching for the dependence of QPO data on accretion-related parameters, we find a correlation between the lower kHz QPO frequency and the parameter combining mass accretion rate with magnetic field strength. The correlation cannot be adequately described by a simple power law due to observed scattering of individual source data in the ensemble of Z and atoll sources. Based on disk-magnetosphere boundary region, the model function for QPO frequency can delineate the correlation taking into account the scattering of individual sources. In addition to mass accretion rate and magnetic field strength, the model function also depends on the radial width of the boundary region near the magnetopause. Modelling the variation of the width with mass accretion rate, we also provide an explanation for the parallel tracks phenomenon observed in the case of individual sources.

  12. Atmospheric Electric Field Measurements at 100 Hz and High Frequency Electric Phenomena

    NASA Astrophysics Data System (ADS)

    Conceição, Ricardo; Gonçalves da Silva, Hugo; Matthews, James; Bennett, Alec; Chubb, John

    2016-04-01

    Spectral response of Atmospheric Electric Potential Gradient (PG), symmetric to the Atmospheric Electric Field, gives important information about phenomena affecting these measurements with characteristic time-scales that appear in the spectra as specific periodicities. This is the case of urban pollution that has a clear weekly dependence and reveals itself on PG measurements by a ~7 day periodicity (Silva et al., 2014). While long-term time-scales (low frequencies) have been exhaustively explored in literature, short-term time-scales (high frequencies), above 1 Hz, have comparatively received much less attention (Anisimov et al., 1999). This is mainly because of the technical difficulties related with the storage of such a huge amount of data (for 100 Hz sampling two days of data uses a ~1 Gb file) and the response degradation of the field-meters at such frequencies. Nevertheless, important Electric Phenomena occurs for frequencies above 1 Hz that are worth pursuing, e.g. the Schumann Resonances have a signature of worldwide thunderstorm activity at frequencies that go from ~8 up to ~40 Hz. To that end the present work shows preliminary results on PG measurements at 100 Hz that took place on two clear-sky days (17th and 18th June 2015) on the South of Portugal, Évora (38.50° N, 7.91° W). The field-mill used is a JCI 131F installed in the University of Évora campus (at 2 m height) with a few trees and two buildings in its surroundings (~50 m away). This device was developed by John Chubb (Chubb, 2014) and manufactured by Chilworth (UK). It was calibrated in December 2013 and recent work by the author (who is honored in this study for his overwhelming contribution to atmospheric electricity) reveals basically a flat spectral response of the device up to frequencies of 100 Hz (Chubb, 2015). This makes this device suitable for the study of High Frequency Electric Phenomena. Anisimov, S.V., et al. (1999). On the generation and evolution of aeroelectric structures

  13. Harvesting Low-Frequency (<5 Hz) Irregular Mechanical Energy: A Possible Killer Application of Triboelectric Nanogenerator.

    PubMed

    Zi, Yunlong; Guo, Hengyu; Wen, Zhen; Yeh, Min-Hsin; Hu, Chenguo; Wang, Zhong Lin

    2016-04-26

    Electromagnetic generators (EMGs) and triboelectric nanogenerators (TENGs) are the two most powerful approaches for harvesting ambient mechanical energy, but the effectiveness of each depends on the triggering frequency. Here, after systematically comparing the performances of EMGs and TENGs under low-frequency motion (<5 Hz), we demonstrated that the output performance of EMGs is proportional to the square of the frequency, while that of TENGs is approximately in proportion to the frequency. Therefore, the TENG has a much better performance than that of the EMG at low frequency (typically 0.1-3 Hz). Importantly, the extremely small output voltage of the EMG at low frequency makes it almost inapplicable to drive any electronic unit that requires a certain threshold voltage (∼0.2-4 V), so that most of the harvested energy is wasted. In contrast, a TENG has an output voltage that is usually high enough (>10-100 V) and independent of frequency so that most of the generated power can be effectively used to power the devices. Furthermore, a TENG also has advantages of light weight, low cost, and easy scale up through advanced structure designs. All these merits verify the possible killer application of a TENG for harvesting energy at low frequency from motions such as human motions for powering small electronics and possibly ocean waves for large-scale blue energy. PMID:27077467

  14. Harvesting Low-Frequency (<5 Hz) Irregular Mechanical Energy: A Possible Killer Application of Triboelectric Nanogenerator.

    PubMed

    Zi, Yunlong; Guo, Hengyu; Wen, Zhen; Yeh, Min-Hsin; Hu, Chenguo; Wang, Zhong Lin

    2016-04-26

    Electromagnetic generators (EMGs) and triboelectric nanogenerators (TENGs) are the two most powerful approaches for harvesting ambient mechanical energy, but the effectiveness of each depends on the triggering frequency. Here, after systematically comparing the performances of EMGs and TENGs under low-frequency motion (<5 Hz), we demonstrated that the output performance of EMGs is proportional to the square of the frequency, while that of TENGs is approximately in proportion to the frequency. Therefore, the TENG has a much better performance than that of the EMG at low frequency (typically 0.1-3 Hz). Importantly, the extremely small output voltage of the EMG at low frequency makes it almost inapplicable to drive any electronic unit that requires a certain threshold voltage (∼0.2-4 V), so that most of the harvested energy is wasted. In contrast, a TENG has an output voltage that is usually high enough (>10-100 V) and independent of frequency so that most of the generated power can be effectively used to power the devices. Furthermore, a TENG also has advantages of light weight, low cost, and easy scale up through advanced structure designs. All these merits verify the possible killer application of a TENG for harvesting energy at low frequency from motions such as human motions for powering small electronics and possibly ocean waves for large-scale blue energy.

  15. A Technique for Estimating the Occlusion Effect for Frequencies Below 125 Hz

    PubMed Central

    Stone, Michael A.; Paul, Anna M.; Axon, Patrick; Moore, Brian C.J.

    2014-01-01

    Objectives The level of bone-conducted sound in the auditory meatus is increased at low frequencies by occlusion of the meatus, for example by the earmold of a hearing aid. Physical measures of this “occlusion effect” (OE) require vibration of the skull. In previous research, either self-voicing or audiometric bone-conduction vibrators have been used to produce this vibration, with the result that the OE could not be measured for frequencies below 125 Hz. However, frequencies below this can be important for music perception by hearing aid users. The objective was to develop and evaluate a method that gives a lower-bound estimate of the OE for frequencies below 125 Hz. Design A low-noise amplifier with extended low-frequency response was used to record the output of a miniature microphone inserted into the meatus of participants. The signal came from sounds of the heartbeat and blood flow of the participant, transmitted via bone-conduction through the walls of the meatus. A simultaneous recording was made of the carotid pulse to permit time-locked averaging (and hence noise reduction) of the microphone signal. Recordings were made from seven otologically and audiometrically normal participants, using clinical probe tips to produce the occlusion. Recordings were also made from an overlapping group of nine participants, using fast-setting impression material to provide a more consistent degree of occlusion. The difference in level of the recorded signal for unoccluded and occluded conditions provided a lower bound for the magnitude of the OE. Results The mean OE increased with decreasing frequency, reaching a plateau of about 40 dB for frequencies below 40 Hz. For some individual recordings, the OE reached 50 dB for frequencies below 20 Hz. With occlusion, the heartbeat became audible for most participants. Conclusions The OE can be very large at low frequencies. The use of hearing aids with closed fittings, which may be employed either to prevent acoustic

  16. Discriminating ripple-fire explosions with high frequency (>20 Hz) data

    SciTech Connect

    Carr, D.B.; Garbin, H.D.

    1996-04-01

    With a Comprehensive Test Ban (CTB), discriminating ripple-fired explosions from mining operations becomes important. Different methods have been proposed to discriminate these explosions, most of which use the modulations seen in the spectra of ripple-fired blasts. The Deployable Seismic Verification System (DSVS) in Wyoming records data at frequencies up to 50 Hz, and provides an opportunity to determine if there are any operational benefits to discriminate ripple-fired explosions from using high frequency (> 20 Hz) data. We collected a database of 646 events consisting of 118 known earthquakes, 1 known rockburst, 176 known ripple-fired quarry blasts and 351 unknown signals. Binary spectrograms for each event were calculated using a 2.5 second window, 5/8 overlap and 10% cosine window. We used a frequency band of 0 to 50 Hz. A blind test was done to choose events that appeared to have spectral banding indicative of ripple-fire explosions. One hundred fifty one events were picked as ripple-fire explosions by both authors; 59 of these events are known quarry blasts. To remove the ambiguities introduced using human analysts, we calculated an average binary spectrum for each event following a method similar to Wuster (1993). A criterion was developed so that events with six or more peaks over 0.8 and/or nulls under 0.2 was declared a ripple-fire explosion. With this method, 251 events were chosen as ripple-fire explosions, 91 of them known quarry blasts.

  17. Upgrading a high-throughput spectrometer for high-frequency (<400 kHz) measurements

    NASA Astrophysics Data System (ADS)

    Nishizawa, T.; Nornberg, M. D.; Den Hartog, D. J.; Craig, D.

    2016-11-01

    The upgraded spectrometer used for charge exchange recombination spectroscopy on the Madison Symmetric Torus resolves emission fluctuations up to 400 kHz. The transimpedance amplifier's cutoff frequency was increased based upon simulations comparing the change in the measured photon counts for time-dynamic signals. We modeled each signal-processing stage of the diagnostic and scanned the filtering frequency to quantify the uncertainty in the photon counting rate. This modeling showed that uncertainties can be calculated based on assuming each amplification stage is a Poisson process and by calibrating the photon counting rate with a DC light source to address additional variation.

  18. Human exposure standards in the frequency range 1 Hz To 100 kHz: the case for adoption of the IEEE standard.

    PubMed

    Patrick Reilly, J

    2014-10-01

    Differences between IEEE C95 Standards (C95.6-2002 and C95.1-2005) in the low-frequency (1 Hz-100 kHz) and the ICNIRP-2010 guidelines appear across the frequency spectrum. Factors accounting for lack of convergence include: differences between the IEEE standards and the ICNIRP guidelines with respect to biological induction models, stated objectives, data trail from experimentally derived thresholds through physical and biological principles, selection and justification of safety/reduction factors, use of probability models, compliance standards for the limbs as distinct from the whole body, defined population categories, strategies for central nervous system protection below 20 Hz, and correspondence of environmental electric field limits with contact currents. This paper discusses these factors and makes the case for adoption of the limits in the IEEE standards.

  19. Discovery of a Neutron Star with Spin Frequency 530 Hz in A1744-361

    NASA Technical Reports Server (NTRS)

    Bhattacharyya, Sudip; Strohmayer, Tod E.; Markwardt, Craig B.; Swank, Jean H.; Bhattacharyya, Sudip

    2005-01-01

    We report the detection with the Rossi X-ray Timing Explorer (RXTE) Proportional Counter Array (PCA) of 530 Hz burst oscillations in a thermonuclear (Type I) burst from the transient X-ray source A1744-361. This is only the second burst ever observed from this source, and the first to be seen in any detail. Our results confirm that A1744-361 is a low mass X-ray binary (LMXB) system harboring a rapidly rotating neutron star. The oscillations are first detected along the rising edge of the burst, and show evidence for frequency evolution of a magnitude similar to that seen in other burst sources. The modulation amplitude and its increase with photon energy are also typical of burst oscillations. The lack of any strong indication of photospheric radius expansion during the burst suggests a 9 kpc upper limit of the source distance. We also find energy dependent dips, establishing A1744-361 as a high inclination, dipping LMXB. The timescale between the two episodes of observed dips suggests an orbital period of approx. 97 min. We have also detected a 2 - 4 Hz quasi-periodic-oscillation (QPO) for the first time from this source. This QPO appears consistent with approx. 1 Hz QPOs seen from other high inclination systems. We searched for kilohertz QPOs, and found a suggestive 2.3 sigma feature at 800 Hz in one observation. The frequency, strength and quality factor are consistent with that of a lower frequency kilohertz QPO, but the relatively low significance argues for caution, so we consider this a tentative detection requiring confirmation.

  20. Low frequency band gaps below 10 Hz in radial flexible elastic metamaterial plate

    NASA Astrophysics Data System (ADS)

    Gao, Nansha; Hou, Hong; Wu, Jiu Hui; Cheng, Baozhu

    2016-11-01

    This paper presents the low frequency acoustic properties of a new proposed elastic metamaterial, which is arranged in the axial coordinate. The band structures, transmission spectra, and eigenmode displacement fields of this metamaterial are different from previous elastic metamaterial structures. Numerical calculation results show that the first order band gap of the radial flexible elastic metamaterial plate is below 10 Hz. A multiple-vibration coupling mechanism is proposed to explain the low frequency band gaps. By changing the geometrical dimensions h 1, h 2, b 1, and b 1 of the centre part, the location and width of the low frequency band gaps can be varied easily. The effects of density and Young’s modulus are also discussed in detail. In summary, the radial flexible elastic metamaterial plate can restrain low frequency vibration, owing to which it can potentially be used to protect infrasound, generate filters, and design acoustic devices.

  1. Dielectric dispersion of water in the frequency range from 10 mHz to 30 MHz.

    PubMed

    Batalioto, F; Duarte, A R; Barbero, G; Neto, A M F

    2010-03-18

    We investigate the dielectric dispersion of water, specially in the low-frequency range, by using the impedance spectroscopy technique. The frequency dependencies of the real R and imaginary chi parts of the impedance could not be explained by means of the usual description of the dielectric properties of the water as an insulating liquid containing ions. This is due to the incomplete knowledge of the parameters entering in the fundamental equations describing the evolution of the system, and on the mechanisms regulating the exchange of charge of the cell with the external circuit. We propose a simple description of our experimental data based on the model of Debye, by invoking a dc conductivity of the cell, related to the nonblocking character of the electrodes. A discussion on the electric circuits able to simulate the cell under investigation, based on bulk and surface elements, is also reported. We find that the simple circuit formed by a series of two parallels of resistance and capacitance is able to reproduce the experimental data concerning the real and imaginary part of the electrical impedance of the cell for frequency larger than 1 Hz. According to this description, one of the parallels takes into account the electrical properties of interface between the electrode and water, and the other of the bulk. For frequency lower than 1 Hz, a good agreement with the experimental data is obtained by simulating the electrical properties of the interface by means of the constant phase element.

  2. Dielectric dispersion of water in the frequency range from 10 mHz to 30 MHz.

    PubMed

    Batalioto, F; Duarte, A R; Barbero, G; Neto, A M F

    2010-03-18

    We investigate the dielectric dispersion of water, specially in the low-frequency range, by using the impedance spectroscopy technique. The frequency dependencies of the real R and imaginary chi parts of the impedance could not be explained by means of the usual description of the dielectric properties of the water as an insulating liquid containing ions. This is due to the incomplete knowledge of the parameters entering in the fundamental equations describing the evolution of the system, and on the mechanisms regulating the exchange of charge of the cell with the external circuit. We propose a simple description of our experimental data based on the model of Debye, by invoking a dc conductivity of the cell, related to the nonblocking character of the electrodes. A discussion on the electric circuits able to simulate the cell under investigation, based on bulk and surface elements, is also reported. We find that the simple circuit formed by a series of two parallels of resistance and capacitance is able to reproduce the experimental data concerning the real and imaginary part of the electrical impedance of the cell for frequency larger than 1 Hz. According to this description, one of the parallels takes into account the electrical properties of interface between the electrode and water, and the other of the bulk. For frequency lower than 1 Hz, a good agreement with the experimental data is obtained by simulating the electrical properties of the interface by means of the constant phase element. PMID:20178324

  3. Exposure to high-frequency electromagnetic fields (100 kHz-2 GHz) in Extremadura (Spain).

    PubMed

    Rufo, M Montaña; Paniagua, Jesús M; Jiménez, Antonio; Antolín, Alicia

    2011-12-01

    The last decade has seen a rapid increase in people's exposure to electromagnetic fields. This paper reports the measurements of radiofrequency (RF) total power densities and power density spectra in 35 towns of the region of Extremadura, Spain. The spectra were taken with three antennas covering frequencies from 100 kHz to 2.2 GHz. This frequency range includes AM/FM radio broadcasting, television, and cellular telephone signals. The power density data and transmitting antenna locations were stored in a geographic information system (GIS) as an aid in analyzing and interpreting the results. The results showed the power density levels to be below the reference level guidelines for human exposure and that the power densities are different for different frequency ranges and different size categories of towns.

  4. Exposure to high-frequency electromagnetic fields (100 kHz-2 GHz) in Extremadura (Spain).

    PubMed

    Rufo, M Montaña; Paniagua, Jesús M; Jiménez, Antonio; Antolín, Alicia

    2011-12-01

    The last decade has seen a rapid increase in people's exposure to electromagnetic fields. This paper reports the measurements of radiofrequency (RF) total power densities and power density spectra in 35 towns of the region of Extremadura, Spain. The spectra were taken with three antennas covering frequencies from 100 kHz to 2.2 GHz. This frequency range includes AM/FM radio broadcasting, television, and cellular telephone signals. The power density data and transmitting antenna locations were stored in a geographic information system (GIS) as an aid in analyzing and interpreting the results. The results showed the power density levels to be below the reference level guidelines for human exposure and that the power densities are different for different frequency ranges and different size categories of towns. PMID:22048492

  5. Review of Studies Concerning Electromagnetic Field (EMF) Exposure Assessment in Europe: Low Frequency Fields (50 Hz-100 kHz).

    PubMed

    Gajšek, Peter; Ravazzani, Paolo; Grellier, James; Samaras, Theodoros; Bakos, József; Thuróczy, György

    2016-01-01

    We aimed to review the findings of exposure assessment studies done in European countries on the exposure of the general public to low frequency electric and magnetic fields (EMFs) of various frequencies. The study shows that outdoor average extremely low frequency magnetic fields (ELF-MF) in public areas in urban environments range between 0.05 and 0.2 µT in terms of flux densities, but stronger values (of the order of a few µT) may occur directly beneath high-voltage power lines, at the walls of transformer buildings, and at the boundary fences of substations. In the indoor environment, high values have been measured close to several domestic appliances (up to the mT range), some of which are held close to the body, e.g., hair dryers, electric shavers. Common sources of exposure to intermediate frequencies (IF) include induction cookers, compact fluorescent lamps, inductive charging systems for electric cars and security or anti-theft devices. No systematic measurement surveys or personal exposimetry data for the IF range have been carried out and only a few reports on measurements of EMFs around such devices are mentioned. According to the available European exposure assessment studies, three population exposure categories were classified by the authors regarding the possible future risk analysis. This classification should be considered a crucial advancement for exposure assessment, which is a mandatory step in any future health risk assessment of EMFs exposure. PMID:27598182

  6. Review of Studies Concerning Electromagnetic Field (EMF) Exposure Assessment in Europe: Low Frequency Fields (50 Hz-100 kHz).

    PubMed

    Gajšek, Peter; Ravazzani, Paolo; Grellier, James; Samaras, Theodoros; Bakos, József; Thuróczy, György

    2016-09-01

    We aimed to review the findings of exposure assessment studies done in European countries on the exposure of the general public to low frequency electric and magnetic fields (EMFs) of various frequencies. The study shows that outdoor average extremely low frequency magnetic fields (ELF-MF) in public areas in urban environments range between 0.05 and 0.2 µT in terms of flux densities, but stronger values (of the order of a few µT) may occur directly beneath high-voltage power lines, at the walls of transformer buildings, and at the boundary fences of substations. In the indoor environment, high values have been measured close to several domestic appliances (up to the mT range), some of which are held close to the body, e.g., hair dryers, electric shavers. Common sources of exposure to intermediate frequencies (IF) include induction cookers, compact fluorescent lamps, inductive charging systems for electric cars and security or anti-theft devices. No systematic measurement surveys or personal exposimetry data for the IF range have been carried out and only a few reports on measurements of EMFs around such devices are mentioned. According to the available European exposure assessment studies, three population exposure categories were classified by the authors regarding the possible future risk analysis. This classification should be considered a crucial advancement for exposure assessment, which is a mandatory step in any future health risk assessment of EMFs exposure.

  7. The phonological function of vowels is maintained at fundamental frequencies up to 880 Hz.

    PubMed

    Friedrichs, Daniel; Maurer, Dieter; Dellwo, Volker

    2015-07-01

    In a between-subject perception task, listeners either identified full words or vowels isolated from these words at F0s between 220 and 880 Hz. They received two written words as response options (minimal pair with the stimulus vowel in contrastive position). Listeners' sensitivity (A') was extremely high in both conditions at all F0s, showing that the phonological function of vowels can also be maintained at high F0s. This indicates that vowel sounds may carry strong acoustic cues departing from common formant frequencies at high F0s and that listeners do not rely on consonantal context phenomena for their identification performance. PMID:26233058

  8. 200 Hz repetition frequency joule-level high beam quality Nd:YAG nanosecond laser

    NASA Astrophysics Data System (ADS)

    Qiu, Jisi; Tang, Xiongxin; Fan, Zhongwei; Wang, Haocheng

    2016-06-01

    A joule-level Nd:YAG nanosecond laser of high repetition frequency and high beam quality is developed out. The laser is designed as a MOPA system mainly including single longitudinal mode seed, pre-amplifier unit an d power amplifier unit. In order to obtain the high-quality laser beam output, phase conjugation is adopted to compensate the laser beam distortion. Under the condition of 200 Hz high repetition frequency and 8.19 μJ single pulse energy injected by the single longitudinal mode seed, 1.53 J output energy is gained. The output laser beam is of 9 mm diameter, 7.41 ns pulse width, the far field beam spot 1.32 times the value of the diffraction limit, 1.2% energy stability (RMS) and less than 13 μrad far field beam spot angle shift.

  9. Copper bromide vapor brightness amplifiers with 100 kHz pulse repetition frequency

    NASA Astrophysics Data System (ADS)

    Trigub, M. V.; Evtushenko, G. S.; Torgaev, S. N.; Shiyanov, D. V.; Evtushenko, T. G.

    2016-10-01

    The paper presents a laser monitor with 10 μs time-resolution based on a high-frequency copper bromide vapor brightness amplifier. A sync circuit has been designed for single-pulse imaging. The analysis of amplifying characteristics of the active elements and active optical system (laser monitor) parameters allowed to determine the optimal concentration of HBr at which the images can be obtained with minimum distortions. For the active element operating at high frequencies (more than 50 kHz) as a brightness amplifier, the concentration of HBr must be lower than that needed for obtaining the maximum output power. The limiting brightness temperature of the background radiation which does not affect the image quality is determined. The potential feasibility of using a proposed brightness amplifier for visualizing processes blocked from viewing by the background radiation with the brightness temperature up to 8000 K is demonstrated.

  10. Possible generation mechanisms of low-frequency waves /less than about 50 Hz/ with application to the bow shock plasma

    NASA Technical Reports Server (NTRS)

    Dangelo, N.

    1979-01-01

    Generation mechanisms of waves observed at the earth's bow shock or in its vicinity within the frequency range extending up to about 50 Hz are reviewed. Observations and theories regarding waves in the solar wind upstream of the bow shock (both low-frequency 0.01-0.05 Hz and high-frequency 0.5-4 Hz waves), waves in the bow shock itself and magnetosheath waves arising from processes of generation or amplification in the bow shock are considered. Hydromagnetic, ion-acoustic and whistler type waves are discussed.

  11. Loading frequencies up to 20Hz as an alternative to accelerate fatigue strength tests in a Y-TZP ceramic.

    PubMed

    Fraga, Sara; Pereira, Gabriel Kalil Rocha; Freitas, Mariana; Kleverlaan, Cornelis Johannes; Valandro, Luiz Felipe; May, Liliana Gressler

    2016-08-01

    Considering the interest of the research community in the fatigue behavior of all-ceramic restorations and the time consumed in low-frequency cyclic fatigue tests, this study aimed to investigate the influence of the loading frequency on the zirconia fatigue strength. The biaxial flexural fatigue strength of Y-TZP discs was determined by the staircase approach after 500,000 cycles. The investigated frequencies were 2Hz (control-simulation of the chewing activity; n=20), 10Hz (n=20), 20Hz (n=20), and 40Hz (n=21). The fatigue strength data were analyzed using one-way ANOVA and post-hoc Tukey׳s test (α=0.05). Pearson coefficient (r) was calculated to assess the existence of a correlation between fatigue strength and loading frequency. X-ray diffraction analysis was used to determine the relative amount of monoclinic phase under each fatigue test condition. The fatigue strength was significantly higher for 40Hz group (630.7±62.1MPa) and did not differ among the groups 2Hz (550.3±89.7MPa), 10Hz (574.0±47MPa) and 20Hz (605.1±30.7MPa). Pearson correlation coefficient indicated a significantly moderate correlation (r=0.57) between fatigue strength and loading frequency. The percentage of monoclinic phase was similar among the groups. Therefore, the use of loading frequencies up to 20Hz seems a good alternative to expedite the cycling strength fatigue tests in polycrystalline ceramics without significantly changing the fatigue behavior showed by zirconia in tests employing the frequency of the masticatory cycle. PMID:26849030

  12. Loading frequencies up to 20Hz as an alternative to accelerate fatigue strength tests in a Y-TZP ceramic.

    PubMed

    Fraga, Sara; Pereira, Gabriel Kalil Rocha; Freitas, Mariana; Kleverlaan, Cornelis Johannes; Valandro, Luiz Felipe; May, Liliana Gressler

    2016-08-01

    Considering the interest of the research community in the fatigue behavior of all-ceramic restorations and the time consumed in low-frequency cyclic fatigue tests, this study aimed to investigate the influence of the loading frequency on the zirconia fatigue strength. The biaxial flexural fatigue strength of Y-TZP discs was determined by the staircase approach after 500,000 cycles. The investigated frequencies were 2Hz (control-simulation of the chewing activity; n=20), 10Hz (n=20), 20Hz (n=20), and 40Hz (n=21). The fatigue strength data were analyzed using one-way ANOVA and post-hoc Tukey׳s test (α=0.05). Pearson coefficient (r) was calculated to assess the existence of a correlation between fatigue strength and loading frequency. X-ray diffraction analysis was used to determine the relative amount of monoclinic phase under each fatigue test condition. The fatigue strength was significantly higher for 40Hz group (630.7±62.1MPa) and did not differ among the groups 2Hz (550.3±89.7MPa), 10Hz (574.0±47MPa) and 20Hz (605.1±30.7MPa). Pearson correlation coefficient indicated a significantly moderate correlation (r=0.57) between fatigue strength and loading frequency. The percentage of monoclinic phase was similar among the groups. Therefore, the use of loading frequencies up to 20Hz seems a good alternative to expedite the cycling strength fatigue tests in polycrystalline ceramics without significantly changing the fatigue behavior showed by zirconia in tests employing the frequency of the masticatory cycle.

  13. Band limited emission with central frequency around 2 Hz accompanying powerful cyclones

    NASA Technical Reports Server (NTRS)

    Troitskaia, V. A.; Shepetnov, K. S.; Dvobnia, B. D.

    1992-01-01

    It has been found that powerful cyclones are proceeded, accompanied and followed by narrow band electromagnetic emission with central frequency around 2 Hz. It is shown that the signal from this emission is unique and clearly distinguishable from known types of magnetic pulsations, spectra of local thunderstorms, and signals from industrial sources. This emission was first observed during an unusually powerful cyclone with tornadoes in the western European part of the Soviet Union, which passed by the observatory of Borok from south to north-east. The emission has been confirmed by analysis of similar events in Antarctica. The phenomenon described presents a new aspect of interactions of processes in the lower atmosphere and the ionosphere.

  14. Precise measurement of dielectric properties at frequencies from 1 kHz to 100 MHz

    NASA Astrophysics Data System (ADS)

    Kakimoto, Akira; Etoh, Akihiro; Hirano, Kaoru; Nonaka, Satoshi

    1987-02-01

    This paper describes an improved apparatus to measure dielectric constants and dissipation factors using a resonance technique. The measurements can be made rapidly and accurately without appreciable systematic error in the wide frequency range from 1 kHz to 100 MHz. This apparatus uses the half power-gap variation method or the half power-varying gap-immersion method for solid-plate specimens and the solid-plate displacement method for liquid specimens. The electrode system is 30 mm in diameter and has a shield ring to avoid the edge capacitance effect, guards against surface current leakage, and variable air capacitors to set the electrode gap at any arbitrary value. To detect a very small power loss, the resonance voltages in circuits with Q≂100 are stabilized to -86 dB at a constant ambient temperature. We use phase detectors so that the electrode gap and the voltage at resonance can easily be read from the digital panel meter and the digital voltmeter. No corrections are necessary even at a high frequency of 100 MHz. The accuracy of measurements made using the half power-varying gap-immersion method is within 0.2% for the dielectric constant and 3% for the dissipation factor without marked degradation over the entire frequency range.

  15. 486nm blue laser operating at 500 kHz pulse repetition frequency

    NASA Astrophysics Data System (ADS)

    Creeden, Daniel; Blanchard, Jon; Pretorius, Herman; Limongelli, Julia; Setzler, Scott D.

    2016-03-01

    Compact, high power blue light in the 470-490nm region is difficult to generate due to the lack of laser sources which are easily convertible (through parametric processes) to those wavelengths. By using a pulsed Tm-doped fiber laser as a pump source for a 2-stage second harmonic generation (SHG) scheme, we have generated ~2W of 486.5nm light at 500kHz pulse repetition frequency (PRF). To our knowledge, this is the highest PRF and output power achieved in the blue region based on a frequency converted, monolithic fiber laser. This pump laser is a pulsed Tm-doped fiber laser/amplifier which generates 12.8W of 1946nm power at 500kHz PRF with diffraction-limited output from a purely single-mode fiber. The output from this laser is converted to 973nm through second harmonic generation (SHG). The 973nm is then converted to 486.5nm via another SHG stage. This architecture operates with very low peak power, which can be challenging from a nonlinear conversion standpoint. However, the low peak power enables the use of a single-mode monolithic fiber amplifier without undergoing nonlinear effects in the fiber. This also eliminates the need for novel fiber designs, large-mode area fiber, or free-space coupling to rod-type amplifiers, improving reliability and robustness of the laser source. Higher power and conversion efficiency are possible through the addition of Tm-doped fiber amplification stages as well as optimization of the nonlinear conversion process and nonlinear materials. In this paper, we discuss the laser layout, results, and challenges with generating blue light using a low peak power approach.

  16. PULSE AMPLITUDE DEPENDS ON kHz QPO FREQUENCY IN THE ACCRETING MILLISECOND PULSAR SAX J1808.4-3658

    SciTech Connect

    Bult, Peter; Van der Klis, Michiel

    2015-01-10

    We study the relation between the 300-700 Hz upper kHz quasi-periodic oscillation (QPO) and the 401 Hz coherent pulsations across all outbursts of the accreting millisecond X-ray pulsar SAX J1808.4-3658 observed with the Rossi X-ray Timing Explorer. We find that the pulse amplitude systematically changes by a factor of ∼2 when the upper kHz QPO frequency passes through 401 Hz: it halves when the QPO moves to above the spin frequency and doubles again on the way back. This establishes for the first time the existence of a direct effect of kHz QPOs on the millisecond pulsations and provides a new clue to the origin of the upper kHz QPO. We discuss several scenarios and conclude that while more complex explanations can not formally be excluded, our result strongly suggests that the QPO is produced by azimuthal motion at the inner edge of the accretion disk, most likely orbital motion. Depending on whether this azimuthal motion is faster or slower than the spin, the plasma then interacts differently with the neutron-star magnetic field. The most straightforward interpretation involves magnetospheric centrifugal inhibition of the accretion flow that sets in when the upper kHz QPO becomes slower than the spin.

  17. Evaluation of the developmental toxicity of 60 Hz magnetic fields and harmonic frequencies in Sprague-Dawley rats.

    PubMed

    Ryan, B M; Polen, M; Gauger, J R; Mallett, E; Kearns, M B; Bryan, T L; McCormick, D L

    2000-05-01

    Experimental data suggest that exposure to the 50 and 60 Hz sinusoidal components of power-frequency magnetic fields (MFs) does not have an adverse impact on fetal development. However, the possible developmental toxicity of MF harmonics has not been investigated. This study was designed to determine whether exposure to 180 Hz MFs (third harmonic), alone or in combination with 60 Hz MFs, induces birth defects in Sprague-Dawley rats. Groups of sperm-positive dams (> or =20/group) were exposed for 18.5 h per day from gestation days 6 through 19 to (1) ambient MFs only (<0.0001 mT; sham controls); (2) 60 Hz MFs at 0.2 mT; (3) 180 Hz MFs at 0.2 mT; or (4) 60 Hz + 180 Hz MFs (10% third harmonic; total field strength = 0.2 mT). Litter size, litter weight, percentage live births, sex ratio, and number of resorption sites were determined for each dam, and gross external, visceral, cephalic and skeletal examinations were performed on all fetuses. MF exposure had no significant effects on litter size, litter weight, or fetal development. With the exception of common rib variants, the incidence of fetal anomalies was comparable in all groups. A small increase in the incidence of rib variants was seen in the group exposed to 60 Hz + 180 Hz MFs; however, the incidence of rib variants in this group was similar to that in historical controls from our laboratory. These data extend the existing database on developmental toxicity of MFs by demonstrating that exposure to 180 Hz MFs, either alone or superimposed on an underlying 60 Hz signal, does not induce biologically significant developmental toxicity. These data do not support the hypothesis that exposure to power-frequency MFs is an important risk factor for fetal development. PMID:10790286

  18. Dielectric properties of skeletal muscle during ischemia in the frequency range from 50 Hz to 200 MHz.

    PubMed

    Schäfer, M; Kirlum, H J; Schlegel, C; Gebhard, M M

    1999-04-20

    The complex dielectric properties of canine skeletal muscles were measured at 25 degrees C during ischemia in the frequency range from 50 Hz to 200 MHz. The dielectric spectrum of skeletal muscle shows an alpha-dispersion below 1 kHz and a beta-dispersion with a relaxation frequency of about 100 kHz. The alpha-dispersion disappears between 450 and 500 min of ischemia time, the same time during which mechanical contraction was observed, and was restored later. During ischemia, the beta-dispersion is shifted continuously to higher frequencies; and at frequencies above 50 MHz, a decrease of the real part of the dielectric permittivity was measured. The dielectric loss factor decreases during ischemia at frequencies below 500 kHz, only interrupted by a short increase, coinciding with the disappearance of the alpha-dispersion. The principal processes that happen during ischemia inside the skeletal muscle tissues were studied with the help of a model especially designed to simulate membrane effects on the dielectric spectrum. The disappearance of the alpha-dispersion is explained by an increase of conductivity in the membrane of the sarcoplasmic reticulum. Shifting beta-dispersion to higher frequencies is a result of metabolically produced ions and therefore increasing conductivity of the intracellular medium. Decreasing dielectric permittivity at frequencies above 50 MHz and decreasing dielectric loss factor at low frequencies are caused by the cell edema.

  19. Cyclic Stress at mHz Frequencies Aligns Fibroblasts in Direction of Zero Strain

    PubMed Central

    Rubner, Wolfgang; Kirchgeßner, Norbert; Safran, Sam; Hoffmann, Bernd; Merkel, Rudolf

    2011-01-01

    Recognition of external mechanical signals is vital for mammalian cells. Cyclic stretch, e.g. around blood vessels, is one such signal that induces cell reorientation from parallel to almost perpendicular to the direction of stretch. Here, we present quantitative analyses of both, cell and cytoskeletal reorientation of umbilical cord fibroblasts. Cyclic strain of preset amplitudes was applied at mHz frequencies. Elastomeric chambers were specifically designed and characterized to distinguish between zero strain and minimal stress directions and to allow accurate theoretical modeling. Reorientation was only induced when the applied stretch exceeded a specific amplitude, suggesting a non-linear response. However, on very soft substrates no mechanoresponse occurs even for high strain. For all stretch amplitudes, the angular distributions of reoriented cells are in very good agreement with a theory modeling stretched cells as active force dipoles. Cyclic stretch increases the number of stress fibers and the coupling to adhesions. We show that changes in cell shape follow cytoskeletal reorientation with a significant temporal delay. Our data identify the importance of environmental stiffness for cell reorientation, here in direction of zero strain. These in vitro experiments on cultured cells argue for the necessity of rather stiff environmental conditions to induce cellular reorientation in mammalian tissues. PMID:22194961

  20. Report on key comparison COOMET.AUV.A-K5: pressure calibration of laboratory standard microphones in the frequency range 2 Hz to 10 kHz

    NASA Astrophysics Data System (ADS)

    Dobrowolska, D.; Kosterov, A.

    2016-01-01

    This is the final report for regional key comparison COOMET.AUV.A-K5 on the pressure calibration of laboratory standard microphones in the frequency range from 2 Hz to 10 kHz. Two laboratories—Central Office of Measures (GUM)—the national metrology institute for Poland and the State Enterprise Scientific-Research Institute for Metrology of Measurement and Control Systems (DP NDI Systema)— the designated institute for acoustics in Ukraine took part in this comparison with the GUM as a pilot. One travelling type LS1P microphone was circulated to the participants and results in the form of regular calibration certificates were collected. The results of the DP NDI Systema obtained in this comparison were linked to the CCAUV.A-K5 key comparison through the joint participation of the GUM. The degrees of equivalence were computed for DP NDI Systema with respect to the CCAUV.A-K5 key comparison reference value. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCAUV, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  1. 0. 04 Hz relative optical-frequency stability in a 1. 5. mu. m distributed-Bragg-reflector (DBR) laser

    SciTech Connect

    Ishida, O.; Toba, H. ); Tohmori, Y. )

    1989-12-01

    The optical frequency of a 1.5 {mu}m distributed-Bragg-reflector (DBR) laser is stabilized against that of a master laser by heterodyne-type frequency locking with a phase-locked loop (PLL). Despite its wide linewidth of 16 MHz, stable PLL operation with an optical hold-in range of 26 GHz is realized, and residual frequency fluctuations are reduced to 0.04 Hz at an averaging time of 500 s. The combination of DBR laser and PLL is, therefore, suitable for future frequency-controlled light sources. The offset error from the settled frequency caused by the band-limited beat spectrum is also discussed.

  2. Nonequilibrium atmospheric pressure plasma jet using a combination of 50 kHz/2 MHz dual-frequency power sources

    SciTech Connect

    Zhou, Yong-Jie; Yuan, Qiang-Hua; Li, Fei; Wang, Xiao-Min; Yin, Gui-Qin; Dong, Chen-Zhong

    2013-11-15

    An atmospheric pressure plasma jet is generated by dual sinusoidal wave (50 kHz and 2 MHz). The dual-frequency plasma jet exhibits the advantages of both low frequency and radio frequency plasmas, namely, the long plasma plume and the high electron density. The radio frequency ignition voltage can be reduced significantly by using dual-frequency excitation compared to the conventional radio frequency without the aid of the low frequency excitation source. A larger operating range of α mode discharge can be obtained using dual-frequency excitation which is important to obtain homogeneous and low-temperature plasma. A larger controllable range of the gas temperature of atmospheric pressure plasma could also be obtained using dual-frequency excitation.

  3. Low Frequency (11 mHz) Oscillations in H1743-322: A New Class of Black Hole QPOs?

    NASA Technical Reports Server (NTRS)

    Altamirano, D.; Strohmayer, T.

    2012-01-01

    We report the discovery of quasi-periodic oscillations (QPO) at approx 11 mHz in two RXTE observations and one Chandra observation of the black hole candidate HI743-322. The QPO is observed only at the beginning of the 2010 and 2011 outbursts at similar hard color and intensity, suggestive of an accretion state dependence for the QPO. Although its frequency appears to be correlated with Xray intensity on timescales of a day, in successive outbursts eight months apart we measure a QPO frequency that differs by less than approximately equals 0.0015 Hz while the intensity had changed significantly. We show that this 11 mHz QPO is different from the so-called Type-C QPOs seen in black holes and that the mechanisms that produce the two flavors of variability are most probably independent. We compare the 11 mHz QPO with other variability phenomena seen in accreting black holes and neutron stars and conclude that although at 1-2 orders of magnitude lower in frequency, they best resemble the so-called "1 Hz" QPOs seen in dipping neutron star systems. If confirmed, H1743-322 is the first black hole showing this type of variability. Given the unusual characteristics and the hard-state dependence of the 11 mHz QPO, we speculate that these oscillations might instead be related to the radio jets observed in HI743-322. It remains unexplained, however, why similar QPOs have not yet been identified in other black holes and why they have only been seen in the last two outbursts of HI743-322.

  4. Effects of 35 kHz, low-frequency ultrasound application in vitro on human fibroblast morphology and migration patterns.

    PubMed

    Conner-Kerr, Teresa; Malpass, Gloria; Steele, Arhalia; Howlett, Allyn

    2015-03-01

    Low-frequency ultrasound (LFU) in the frequency range 30-40 kHz administered using different delivery methods (waterbath and noncontact spray) has shown positive effects on chronic wound healing rates in humans, but the underlying mechanisms are only beginning to be explored. To examine the effects of LFU delivered at 35 kHz on the morphology and migration of human fibroblasts, real-time videography was used to record the rate and character of cultured human fibroblast migration at 8-hour increments for 48 hours in a wound assay model. Cells were treated with 35 kHz LFU or saline only (control). Cellular morphology (cell shape, packing, and apparent length) and migration patterns including orientation were analyzed using time-lapse videography. LFU delivered at a frequency of 35 kHz produced a different pattern of fibroblast migration in vitro (varied orientation versus vertical orientation for untreated cells) and altered cell morphology compared to controls. The observed pattern of migration was more varied and widely distributed across multiple angles versus the predominant parallel orientation of the migrating untreated cells. The potential implications of these findings on collagen placement in the extracellular matrix, which may affect degree of soft tissue scarring, should be further investigated.

  5. Low-frequency Quasi-periodic Oscillation from the 11 Hz Accreting Pulsar in Terzan 5: Not Frame Dragging

    NASA Astrophysics Data System (ADS)

    Altamirano, D.; Ingram, A.; van der Klis, M.; Wijnands, R.; Linares, M.; Homan, J.

    2012-11-01

    We report on six RXTE observations taken during the 2010 outburst of the 11 Hz accreting pulsar IGR J17480-2446 located in the globular cluster Terzan 5. During these observations we find power spectra which resemble those seen in Z-type high-luminosity neutron star low-mass X-ray binaries, with a quasi-periodic oscillation (QPO) in the 35-50 Hz range simultaneous with a kHz QPO and broadband noise. Using well-known frequency-frequency correlations, we identify the 35-50 Hz QPOs as the horizontal branch oscillations, which were previously suggested to be due to Lense-Thirring (LT) precession. As IGR J17480-2446 spins more than an order of magnitude more slowly than any of the other neutron stars where these QPOs were found, this QPO cannot be explained by frame dragging. By extension, this casts doubt on the LT precession model for other low-frequency QPOs in neutron stars and perhaps even black hole systems.

  6. LOW-FREQUENCY QUASI-PERIODIC OSCILLATION FROM THE 11 Hz ACCRETING PULSAR IN TERZAN 5: NOT FRAME DRAGGING

    SciTech Connect

    Altamirano, D.; Van der Klis, M.; Wijnands, R.; Ingram, A.; Linares, M.; Homan, J.

    2012-11-01

    We report on six RXTE observations taken during the 2010 outburst of the 11 Hz accreting pulsar IGR J17480-2446 located in the globular cluster Terzan 5. During these observations we find power spectra which resemble those seen in Z-type high-luminosity neutron star low-mass X-ray binaries, with a quasi-periodic oscillation (QPO) in the 35-50 Hz range simultaneous with a kHz QPO and broadband noise. Using well-known frequency-frequency correlations, we identify the 35-50 Hz QPOs as the horizontal branch oscillations, which were previously suggested to be due to Lense-Thirring (LT) precession. As IGR J17480-2446 spins more than an order of magnitude more slowly than any of the other neutron stars where these QPOs were found, this QPO cannot be explained by frame dragging. By extension, this casts doubt on the LT precession model for other low-frequency QPOs in neutron stars and perhaps even black hole systems.

  7. In vitro Neurons in Mammalian Cortical Layer 4 Exhibit Intrinsic Oscillatory Activity in the 10- to 50-Hz Frequency Range

    NASA Astrophysics Data System (ADS)

    Llinas, Rodolfo R.; Grace, Anthony A.; Yarom, Yosef

    1991-02-01

    We report here the presence of fast subthreshold oscillatory potentials recorded in vitro from neurons within layer 4 of the guinea pig frontal cortex. Two types of oscillatory neurons were recorded: (i) One type exhibited subthreshold oscillations whose frequency increased with membrane depolarization and encompassed a range of 10-45 Hz. Action potentials in this type of neuron demonstrated clear after-hyperpolarizations. (ii) The second type of neuron was characterized by narrow-frequency oscillations near 35-50 Hz. These oscillations often outlasted the initiating depolarizing stimulus. No calcium component could be identified in their action potential. In both types of cell the subthreshold oscillations were tetrodotoxin-sensitive, indicating that the depolarizing phase of the oscillation was generated by a voltage-dependent sodium conductance. The initial depolarizing phase was followed by a potassium conductance responsible for the falling phase of the oscillatory wave. In both types of cell, the subthreshold oscillation could trigger spikes at the oscillatory frequency, if the membrane was sufficiently depolarized. Combining intracellular recordings with Lucifer yellow staining showed that the narrow-frequency oscillatory activity was produced by a sparsely spinous interneuron located in layer 4 of the cortex. This neuron has extensive local axonal collaterals that ramify in layers 3 and 4 such that they may contribute to the columnar synchronization of activity in the 40- to 50-Hz range. Cortical activity in this frequency range has been proposed as the basis for the "conjunctive properties" of central nervous system networks.

  8. Frequency-modulated 50 kHz ultrasonic vocalizations: a tool for uncovering the molecular substrates of positive affect.

    PubMed

    Burgdorf, Jeffrey; Panksepp, Jaak; Moskal, Joseph R

    2011-10-01

    The evidence that frequency modulated (FM) 50 kHz ultrasonic vocalizations (USVs) reflect a positive emotional state in rats is reviewed. Positive emotional states in humans are measured by facial-vocal displays (e.g., Duchenne smiling and laughter), approach behavior, and subjective self-report of feeling states. In laboratory animals, only facial-vocal displays, along with approach behavior can be measured. FM 50 kHz USVs are uniquely elevated by hedonic stimuli and suppressed by aversive stimuli. Rates of FM 50 kHz USVs are positively correlated to the rewarding value of the eliciting stimulus. Additionally, playbacks of these vocalizations are rewarding. The neural and pharmacological substrates of 50 kHz USVs are consistent with those of human positive affective states. By experimentally eliciting FM 50 kHz USVs, the novel molecular underpinning of positive affect can be elucidated and may be similar to those in humans. In humans, positive emotional states confer resilience to depression and anxiety, as well as promote overall health. Using rough-and-tumble play induced hedonic USVs, we have identified insulin like growth factor I and the NR2B subunit of the NMDA receptor as playing a functional role in positive affective states. From this research, we have developed a promising new class of antidepressants that is entering phase II clinical trials for the treatment of depression. PMID:21144859

  9. 820 Hz linewidth short-linear-cavity single-frequency fiber laser at 1.5 μm

    NASA Astrophysics Data System (ADS)

    Mo, Shupei; Li, Zebiao; Huang, Xiang; Xu, Shanhui; Feng, Zhouming; Zhang, Weinan; Li, Can; Yang, Changsheng; Qian, Qi; Chen, Dongdan; Yang, Zhongmin

    2014-03-01

    We proposed a short-linear-cavity fiber laser with a virtual-folded-ring configuration, which combines the advantages of ring lasers and short-linear-cavity lasers. An all-fiber quarter-wave plate was used inside the cavity to introduce polarization retardation. By retarding the polarization of the travelling waves, the spatial-hole-burning effect was weakened and the efficient cavity length was extended to nearly twice its physical length. As a result, a single-frequency laser output with a linewidth of less than 820 Hz was obtained from the free-running fiber laser. The relaxation oscillation frequency was observed to be around 280 kHz and the signal to noise ratio of the laser output was >72 dB.

  10. 200 kHz Commercial Sonar Systems Generate Lower Frequency Side Lobes Audible to Some Marine Mammals

    SciTech Connect

    Deng, Zhiqun; Southall, Brandon; Carlson, Thomas J.; Xu, Jinshan; Martinez, Jayson J.; Weiland, Mark A.; Ingraham, John M.

    2014-04-15

    The spectral properties of pulses transmitted by three commercially available 200 kHz echo sounders were measured to assess the possibility that sound energy in below the center (carrier) frequency might be heard by marine mammals. The study found that all three sounders generated sound at frequencies below the center frequency and within the hearing range of some marine mammals and that this sound was likely detectable by the animals over limited ranges. However, at standard operating source levels for the sounders, the sound below the center frequency was well below potentially harmful levels. It was concluded that the sounds generated by the sounders could affect the behavior of marine mammals within fairly close proximity to the sources and that that the blanket exclusion of echo sounders from environmental impact analysis based solely on the center frequency output in relation to the range of marine mammal hearing should be reconsidered.

  11. 30 Hz-linewidth, diode-laser-pumped, Nd:GGG nonplanar ring oscillators by active frequency stabilisation

    NASA Technical Reports Server (NTRS)

    Day, T.; Nilsson, A. C.; Fejer, M. M.; Farinas, A. D.; Gustafson, E. K.

    1989-01-01

    A heterodyne linewidth of less than 30 Hz for the beatnote between the outputs of two 282 THz Nd:GGG nonplanar ring oscillators (NPROs) is reported. The lasers were independently locked to adjacent axial modes of a high-finesse interferometer. The remnant frequency noise appears to be dominated by free spectral range fluctuations in the reference interferometer rather than by residual laser noise.

  12. Effective conductivity and permittivity of unsaturated porous materials in the frequency range 1 mHz-1GHz.

    PubMed

    Revil, A

    2013-01-01

    A model combining low-frequency complex conductivity and high-frequency permittivity is developed in the frequency range from 1 mHz to 1 GHz. The low-frequency conductivity depends on pore water and surface conductivities. Surface conductivity is controlled by the electrical diffuse layer, the outer component of the electrical double layer coating the surface of the minerals. The frequency dependence of the effective quadrature conductivity shows three domains. Below a critical frequency fp , which depends on the dynamic pore throat size Λ, the quadrature conductivity is frequency dependent. Between fp and a second critical frequency fd , the quadrature conductivity is generally well described by a plateau when clay minerals are present in the material. Clay-free porous materials with a narrow grain size distribution are described by a Cole-Cole model. The characteristic frequency fd controls the transition between double layer polarization and the effect of the high-frequency permittivity of the material. The Maxwell-Wagner polarization is found to be relatively negligible. For a broad range of frequencies below 1 MHz, the effective permittivity exhibits a strong dependence with the cation exchange capacity and the specific surface area. At high frequency, above the critical frequency fd , the effective permittivity reaches a high-frequency asymptotic limit that is controlled by the two Archie's exponents m and n like the low-frequency electrical conductivity. The unified model is compared with various data sets from the literature and is able to explain fairly well a broad number of observations with a very small number of textural and electrochemical parameters. It could be therefore used to interpret induced polarization, induction-based electromagnetic methods, and ground penetrating radar data to characterize the vadose zone.

  13. 200 kHz commercial sonar systems generate lower frequency side lobes audible to some marine mammals.

    PubMed

    Deng, Z Daniel; Southall, Brandon L; Carlson, Thomas J; Xu, Jinshan; Martinez, Jayson J; Weiland, Mark A; Ingraham, John M

    2014-01-01

    The spectral properties of pulses transmitted by three commercially available 200 kHz echo sounders were measured to assess the possibility that marine mammals might hear sound energy below the center (carrier) frequency that may be generated by transmitting short rectangular pulses. All three sounders were found to generate sound at frequencies below the center frequency and within the hearing range of some marine mammals, e.g. killer whales, false killer whales, beluga whales, Atlantic bottlenose dolphins, harbor porpoises, and others. The frequencies of these sub-harmonic sounds ranged from 90 to 130 kHz. These sounds were likely detectable by the animals over distances up to several hundred meters but were well below potentially harmful levels. The sounds generated by the sounders could potentially affect the behavior of marine mammals within fairly close proximity to the sources and therefore the exclusion of echo sounders from environmental impact analysis based solely on the center frequency output in relation to the range of marine mammal hearing should be reconsidered. PMID:24736608

  14. 200 kHz Commercial Sonar Systems Generate Lower Frequency Side Lobes Audible to Some Marine Mammals

    PubMed Central

    Deng, Z. Daniel; Southall, Brandon L.; Carlson, Thomas J.; Xu, Jinshan; Martinez, Jayson J.; Weiland, Mark A.; Ingraham, John M.

    2014-01-01

    The spectral properties of pulses transmitted by three commercially available 200 kHz echo sounders were measured to assess the possibility that marine mammals might hear sound energy below the center (carrier) frequency that may be generated by transmitting short rectangular pulses. All three sounders were found to generate sound at frequencies below the center frequency and within the hearing range of some marine mammals, e.g. killer whales, false killer whales, beluga whales, Atlantic bottlenose dolphins, harbor porpoises, and others. The frequencies of these sub-harmonic sounds ranged from 90 to 130 kHz. These sounds were likely detectable by the animals over distances up to several hundred meters but were well below potentially harmful levels. The sounds generated by the sounders could potentially affect the behavior of marine mammals within fairly close proximity to the sources and therefore the exclusion of echo sounders from environmental impact analysis based solely on the center frequency output in relation to the range of marine mammal hearing should be reconsidered. PMID:24736608

  15. Areas V1 and V2 show microsaccade-related 3-4-Hz covariation in gamma power and frequency.

    PubMed

    Lowet, E; Roberts, M J; Bosman, C A; Fries, P; De Weerd, P

    2016-05-01

    Neuronal gamma-band synchronization (25-80 Hz) in visual cortex appears sustained and stable during prolonged visual stimulation when investigated with conventional averages across trials. However, recent studies in macaque visual cortex have used single-trial analyses to show that both power and frequency of gamma oscillations exhibit substantial moment-by-moment variation. This has raised the question of whether these apparently random variations might limit the functional role of gamma-band synchronization for neural processing. Here, we studied the moment-by-moment variation in gamma oscillation power and frequency, as well as inter-areal gamma synchronization, by simultaneously recording local field potentials in V1 and V2 of two macaque monkeys. We additionally analyzed electrocorticographic V1 data from a third monkey. Our analyses confirm that gamma-band synchronization is not stationary and sustained but undergoes moment-by-moment variations in power and frequency. However, those variations are neither random and nor a possible obstacle to neural communication. Instead, the gamma power and frequency variations are highly structured, shared between areas and shaped by a microsaccade-related 3-4-Hz theta rhythm. Our findings provide experimental support for the suggestion that cross-frequency coupling might structure and facilitate the information flow between brain regions.

  16. 200 kHz commercial sonar systems generate lower frequency side lobes audible to some marine mammals.

    PubMed

    Deng, Z Daniel; Southall, Brandon L; Carlson, Thomas J; Xu, Jinshan; Martinez, Jayson J; Weiland, Mark A; Ingraham, John M

    2014-01-01

    The spectral properties of pulses transmitted by three commercially available 200 kHz echo sounders were measured to assess the possibility that marine mammals might hear sound energy below the center (carrier) frequency that may be generated by transmitting short rectangular pulses. All three sounders were found to generate sound at frequencies below the center frequency and within the hearing range of some marine mammals, e.g. killer whales, false killer whales, beluga whales, Atlantic bottlenose dolphins, harbor porpoises, and others. The frequencies of these sub-harmonic sounds ranged from 90 to 130 kHz. These sounds were likely detectable by the animals over distances up to several hundred meters but were well below potentially harmful levels. The sounds generated by the sounders could potentially affect the behavior of marine mammals within fairly close proximity to the sources and therefore the exclusion of echo sounders from environmental impact analysis based solely on the center frequency output in relation to the range of marine mammal hearing should be reconsidered.

  17. Analgesic effects of transcutaneous electrical nerve stimulation and interferential current on experimental ischemic pain models: frequencies of 50 hz and 100 hz.

    PubMed

    Bae, Young-Hyeon; Lee, Suk Min

    2014-12-01

    [Purpose] This study compared the analgesic effects of transcutaneous electrical nerve stimulation (TENS) and interferential currents (IFC) on induced ischemic pain in healthy volunteers. [Subjects] The subjects were 36 volunteers (18 male, 18 female) without known pathology that could cause pain. Their mean age was 24.5±2.2 years. [Methods] A single-blind and parallel-group method was used. Subjects were randomly allocated to receive each 50 Hz TENS, 50 Hz IFC, 100 Hz TENS, and 100 Hz IFC. This study experimentally induced ischemic pain in otherwise pain-free subjects using a modified version of the submaximal effort tourniquet technique. Subjects completed twelve cycles of the ischemic-induced pain test. The primary outcome measure was the change in self-reported of pain intensity during one of four possible treatments. [Results] There were significant effects for Time, which were attributed to a significant reduction in pain intensity for all groups. There were no significant effects for groups or group-time interaction. The 50 Hz IFC treatment was more comfortable than the other treatments in the present study, and it is likely to be better accepted and tolerated by patients. [Conclusion] We conclude that there were no differences in the analgesic effects of the four treatments under the present experimental conditions. The 50 Hz IFC treatment is more comfortable than the other treatments.

  18. Family food involvement and frequency of family dinner meals among Australian children aged 10-12years. Cross-sectional and longitudinal associations with dietary patterns.

    PubMed

    Leech, Rebecca M; McNaughton, Sarah A; Crawford, David A; Campbell, Karen J; Pearson, Natalie; Timperio, Anna

    2014-04-01

    Involvement in meal preparation and eating meals with the family are associated with better dietary patterns in adolescents, however little research has included older children or longitudinal study designs. This 3-year longitudinal study examines cross-sectional and longitudinal associations between family food involvement, family dinner meal frequency and dietary patterns during late childhood. Questionnaires were completed by parents of 188 children from Greater Melbourne, Australia at baseline in 2002 (mean age=11.25years) and at follow-up in 2006 (mean age=14.16years). Principal components analysis (PCA) was used to identify dietary patterns. Factor analysis (FA) was used to determine the principal factors from six indicators of family food involvement. Multiple linear regression models were used to predict the dietary patterns of children and adolescents at baseline and at follow-up, 3years later, from baseline indicators of family food involvement and frequency of family dinner meals. PCA revealed two dietary patterns, labeled a healthful pattern and an energy-dense pattern. FA revealed one factor for family food involvement. Cross-sectionally among boys, family food involvement score (β=0.55, 95% CI: 0.02, 1.07) and eating family dinner meals daily (β=1.11, 95% CI: 0.27, 1.96) during late childhood were positively associated with the healthful pattern. Eating family dinner meals daily was inversely associated with the energy-dense pattern, cross-sectionally among boys (β=-0.56, 95% CI: -1.06, -0.06). No significant cross-sectional associations were found among girls and no significant longitudinal associations were found for either gender. Involvement in family food and eating dinner with the family during late childhood may have a positive influence on dietary patterns of boys. No evidence was found to suggest the effects on dietary patterns persist into adolescence.

  19. Device for recording the 20 Hz - 200 KHz sound frequency spectrum using teletransmission

    NASA Technical Reports Server (NTRS)

    Baciu, I.

    1974-01-01

    The device described consists of two distinct parts: (1) The sound pickup system consisting of the wide-frequency band condenser microphone which contains in the same assembly the frequency-modulated oscillator and the output stage. Being transistorized and small, this system can be easily moved, so that sounds can be picked up even in places that are difficult to reach with larger devices. (2) The receiving and recording part is separate and can be at a great distance from the sound pickup system. This part contains a 72 MHz input stage, a frequency changer that gives an intermediate frequency of 30 MHz and a multichannel analyzer coupled to an oscilloscope and a recorder.

  20. Increase in radiation-induced HPRT gene mutation frequency after nonthermal exposure to nonionizing 60 Hz electromagnetic fields.

    PubMed

    Walleczek, J; Shiu, E C; Hahn, G M

    1999-04-01

    It is widely accepted that moderate levels of nonionizing electric or magnetic fields, for example 50/60 Hz magnetic fields of about 1 mT, are not mutagenic. However, it is not known whether such fields can enhance the action of known mutagens. To explore this question, a stringent experimental protocol, which included blinding and systematic negative controls, was implemented, minimizing the possibility of observer bias or experimental artifacts. As a model system, we chose to measure mutation frequencies induced by 2 Gy gamma rays in the redox-sensitive hypoxanthine-guanine phosphoribosyl transferase (HPRT) gene in Chinese hamster ovary cells. We tested whether a 12-h exposure to a 60 Hz sinusoidally oscillating magnetic-flux density (Brms = 0.7 mT) could affect the mutagenic effects of ionizing radiation on the HPRT gene locus. We determined that the magnetic-field exposure induced an approximate 1.8-fold increase in HPRT mutation frequency. Additional experiments at Brms = 0.23 and 0.47 mT revealed that the effect was reduced at lower flux densities. The field exposure did not enhance radiation-induced cytotoxicity or mutation frequencies in cells not exposed to ionizing radiation. These results suggest that moderate-strength, oscillating magnetic fields may act as an enhancer of mutagenesis in mammalian cells.

  1. High switching speed copper phthalocyanine thin film transistors with cut-off frequency up to 25 kHz

    NASA Astrophysics Data System (ADS)

    Wang, Zeying; Wang, Dong Xing; Zhang, Yongshuang; Wang, Yueyue

    2015-12-01

    The characteristics of high frequency and high speed are demonstrated in vertical structure organic thin film transistors (VOTFTs) fabricated by DC magnetron sputtering and vacuum evaporation. The saturated current-voltage characteristics can be determined by drain-source negative bias voltage. Responsive frequency of the device is as high as 20 kHz when rectangular wave dynamic signal is applied to the gate-source electrode, and switch characteristic time reaches the microsecond. The unsaturated current-voltage characteristics are observed when the drain-source bias voltage is positive. In the condition of VDS = 3 V and VGS = 0 V, the drain-source current IDS is 2.986 × 10-5 A, and the current density is 1.194 mA/cm2. Cut-off frequency fc is 25 kHz when a small sine wave dynamic signal is applied to the gate-source electrode. The volt-ampere characteristic of VOTFTs transfers from linear to nonlinear with increasing of drain-source bias voltage.

  2. Behavioral responses of California sea lions to mid-frequency (3250-3450 Hz) sonar signals.

    PubMed

    Houser, Dorian S; Martin, Stephen W; Finneran, James J

    2013-12-01

    Military sonar has the potential to negatively impact marine mammals. To investigate factors affecting behavioral disruption in California sea lions (Zalophus californianus), fifteen sea lions participated in a controlled exposure study using a simulated tactical sonar signal (1 s duration, 3250-3450 Hz) as a stimulus. Subjects were placed into groups of three and each group received a stimulus exposure of 125, 140, 155, 170, or 185 dB re: 1 μPa (rms). Each subject was trained to swim across an enclosure, touch a paddle, and return to the start location. Sound exposures occurred at the mid-point of the enclosure. Control and exposure sessions were run consecutively and each consisted of ten, 30-s trials. The occurrence and severity of behavioral responses were used to create acoustic dose-response and dose-severity functions. Age of the subject significantly affected the dose-response relationship, but not the dose-severity relationship. Repetitive exposures did not affect the dose-response relationship.

  3. >400 kHz repetition rate wavelength-swept laser and application to high-speed optical frequency domain imaging.

    PubMed

    Oh, Wang-Yuhl; Vakoc, Benjamin J; Shishkov, Milen; Tearney, Guillermo J; Bouma, Brett E

    2010-09-01

    We demonstrate a high-speed wavelength-swept laser with a tuning range of 104 nm (1228-1332 nm) and a repetition rate of 403 kHz. The design of the laser utilizes a high-finesse polygon-based wavelength-scanning filter and a short-length unidirectional ring resonator. Optical frequency domain imaging of the human skin in vivo is presented using this laser, and the system shows sensitivity of higher than 98 dB with single-side ranging depth of 1.7 mm over 4 dB sensitivity roll-off.

  4. On the lack of correlation between X-ray flux and kHz quasi-periodic oscillation frequencies

    NASA Astrophysics Data System (ADS)

    Catmabacak, Onur; Hakan Erkut, M.

    2016-07-01

    We study the so-called "parallel tracks" phenomenon, which arises from the observation that kHz quasi-periodic oscillation (QPO) frequencies correlate with X-ray flux on short time scales (less than a day) while there seems to be no correlation at all on longer time scales (more than a day). The oscillatory modes with frequency bands determined by the radial epicyclic frequency in the magnetic boundary region between the disk and the neutron star magnetosphere are likely to be the origin of these high frequency QPOs. Within the boundary region model, we provide a possible explanation for the parallel track phenomenon taking into account the variation of the model parameters such as the rotation frequency of the innermost disk matter and the radial extension of the boundary region. In addition to the mass, radius, and magnetic field of the neutron star, the frequency bands of oscillatory modes depend on mass accretion rate through these model parameters as well. Using the aspect ratio of the disk, which actually depends on mass accretion rate, we estimate the radial width of the boundary region and its variation on long and short time scales to reproduce the parallel tracks in accordance with observations. We repeat the analysis for a wide range of neutron star masses, radii, and magnetic field strengths in order to understand the effects of these parameters on our results.

  5. Increasing the oscillation frequency of strong magnetic fields above 101 kHz significantly raises peripheral nerve excitation thresholds

    PubMed Central

    Weinberg, Irving N.; Stepanov, Pavel Y.; Fricke, Stanley T.; Probst, Roland; Urdaneta, Mario; Warnow, Daniel; Sanders, Howard; Glidden, Steven C.; McMillan, Alan; Starewicz, Piotr M.; Reilly, J. Patrick

    2012-01-01

    Purpose: A time-varying magnetic field can cause unpleasant peripheral nerve stimulation (PNS) when the maximum excursion of the magnetic field (ΔB) is above a frequency-dependent threshold level [P. Mansfield and P. R. Harvey, Magn. Reson. Med. 29, 746–758 (1993)]. Clinical and research magnetic resonance imaging (MRI) gradient systems have been designed to avoid such bioeffects by adhering to regulations and guidelines established on the basis of clinical trials. Those trials, generally employing sinusoidal waveforms, tested human responses to magnetic fields at frequencies between 0.5 and 10 kHz [W. Irnich and F. Schmitt, Magn. Reson. Med. 33, 619–623 (1995), T. F. Budinger et al., J. Comput. Assist. Tomogr. 15, 909–914 (1991), and D. J. Schaefer et al., J. Magn. Reson. Imaging 12, 20–29 (2000)]. PNS thresholds for frequencies higher than 10 kHz had been extrapolated, using physiological models [J. P. Reilly et al., IEEE Trans. Biomed. Eng. BME-32(12), 1001–1011 (1985)]. The present study provides experimental data on human PNS thresholds to oscillating magnetic field stimulation from 2 to 183 kHz. Sinusoidal waveforms were employed for several reasons: (1) to facilitate comparison with earlier reports that used sine waves, (2) because prior designers of fast gradient hardware for generalized waveforms (e.g., including trapezoidal pulses) have employed quarter-sine-wave resonant circuits to reduce the rise- and fall-times of pulse waveforms, and (3) because sinusoids are often used in fast pulse sequences (e.g., spiral scans) [S. Nowak, U.S. patent 5,245,287 (14 September 1993) and K. F. King and D. J. Schaefer, J. Magn. Reson. Imaging 12, 164–170 (2000)]. Methods: An IRB-approved prospective clinical trial was performed, involving 26 adults, in which one wrist was exposed to decaying sinusoidal magnetic field pulses at frequencies from 2 to 183 kHz and amplitudes up to 0.4 T. Sham exposures (i.e., with no magnetic fields) were applied to all

  6. Aminergic control of high-frequency (approximately 200 Hz) network oscillations in the hippocampus of the behaving rat.

    PubMed

    Ponomarenko, Alexei A; Knoche, Anja; Korotkova, Tatiana M; Haas, Helmut L

    2003-09-11

    Hippocampal high-frequency (200 Hz, 'ripple') oscillations were recorded in the CA1 area of behaving rats. The histamine H1-receptor antagonist pyrilamine facilitated while the H2-antagonist zolantidine (5 mg/kg i.p) transiently decreased ripple occurrence. Thioperamide, an H3 antagonist, had no effect. The 5-HT1A-receptor antagonist WAY100635 (50 microg i.c.v.) reduced the occurrence and the intrinsic frequency of ripples. The 5-HT3-receptor antagonist Y-25130 (i.c.v.) increased the number but reduced the amplitude of ripples. All the treatments affected sharp-waves and ripple oscillations to the same extent. Changes of ripple occurrence were not secondary to alterations of behavior. In the light of these divergent actions via different receptor subtypes the net effect of aminergic innervations will be determined by their state-dependent activities and mutual interactions as well as receptor localizations. PMID:12902028

  7. Integrated mixed signal control IC for 500-kHz switching frequency buck regulator

    NASA Astrophysics Data System (ADS)

    Chen, Keng; Zhang, Hong

    2015-12-01

    The main purpose for this work is to study the challenges of designing a digital buck regulator using pipelined analog to digital converter (ADC). Although pipelined ADC can achieve high sampling speed, it will introduce additional phase lag to the buck circuit. Along with the latency brought by processing time of additional digital circuits, as well as the time delay associated with the switching frequency, the closed loop will be unstable; moreover, raw ADC outputs have low signal-to-noise ratio, which usually need back-end calibration. In order to compensate these phase lag and make control loop unconditional stable, as well as boost up signal-to-noise ratio of the ADC block with cost-efficient design, a finite impulse response filter followed by digital proportional-integral-derivative blocks were designed. All these digital function blocks were optimised with processing speed. In the system simulation, it can be found that this controller achieved output regulation within 10% of nominal 5 V output voltage under 1 A/µs load transient condition; moreover, with the soft-start method, there is no turn-on overshooting. The die size of this controller is controlled within 3 mm2 by using 180 nm CMOS technology.

  8. Magnetoreception in laboratory mice: sensitivity to extremely low-frequency fields exceeds 33 nT at 30 Hz

    PubMed Central

    Prato, Frank S.; Desjardins-Holmes, Dawn; Keenliside, Lynn D.; DeMoor, Janice M.; Robertson, John A.; Thomas, Alex W.

    2013-01-01

    Magnetoreception in the animal kingdom has focused primarily on behavioural responses to the static geomagnetic field and the slow changes in its magnitude and direction as animals navigate/migrate. There has been relatively little attention given to the possibility that weak extremely low-frequency magnetic fields (wELFMF) may affect animal behaviour. Previously, we showed that changes in nociception under an ambient magnetic field-shielded environment may be a good alternative biological endpoint to orientation measurements for investigations into magnetoreception. Here we show that nociception in mice is altered by a 30 Hz field with a peak amplitude more than 1000 times weaker than the static component of the geomagnetic field. When mice are exposed to an ambient magnetic field-shielded environment 1 h a day for five consecutive days, a strong analgesic (i.e. antinociception) response is induced by day 5. Introduction of a static field with an average magnitude of 44 µT (spatial variability of ±3 µT) marginally affects this response, whereas introduction of a 30 Hz time-varying field as weak as 33 nT has a strong effect, reducing the analgesic effect by 60 per cent. Such sensitivity is surprisingly high. Any purported detection mechanisms being considered will need to explain effects at such wELFMF. PMID:23365198

  9. Free-field Calibration of the Pressure Sensitivity of Microphones at Frequencies up to 80 kHz

    NASA Technical Reports Server (NTRS)

    Herring, G. C.; Zuckerwar, Allan J.; Elbing, Brian R.

    2006-01-01

    A free-field (FF) substitution method for calibrating the pressure sensitivity of microphones at frequencies up to 80 kHz is demonstrated with both grazing and normal incidence geometries. The substitution-based method, as opposed to a simultaneous method, avoids problems associated with the non-uniformity of the sound field and, as applied here, uses a 1/2 -inch air-condenser pressure microphone as a known reference. Best results were obtained with a centrifugal fan, which is used as a random, broadband sound source. A broadband source minimizes reflection-related interferences that often plague FF measurements. Calibrations were performed on 1/4-inch FF air-condenser, electret, and micro-electromechanical systems (MEMS) microphones in an anechoic chamber. The accuracy of this FF method is estimated by comparing the pressure sensitivity of an air-condenser microphone, as derived from the FF measurement, with that of an electrostatic actuator calibration and is typically 0.3 dB (95% confidence), over the range 2-80 kHz.

  10. Highly efficient, widely tunable, 10-Hz parametric amplifier pumped by frequency-doubled femtosecond Ti:sapphire laser pulses.

    PubMed

    Zhang, J Y; Xu, Z; Kong, Y; Yu, C; Wu, Y

    1998-05-20

    We report a 10-Hz, highly efficient, widely tunable (from the visible to the IR), broadband femtosecond optical parametric generator and optical parametric amplifier (OPA) in BBO, LBO, and CBO crystals pumped by the frequency-doubled output of a regeneratively amplified Ti:sapphire laser at 400 nm. The output of the system is continuously tunable from 440 nm to 2.5 microm with a maximum overall efficiency of approximately 25% at 670 nm and an optical conversion efficiency of more than 36% in the OPA stage. The effects of the seed beam energy, the type of the crystal and the crystal length, and the pumping energy of the output of the OPA, such as the optical efficiency, the bandwidth, the pulse duration, and the group velocity mismatch between the signal and the idler and between the seeder and the pump, are investigated. The results provide useful information for optimization of the design of the system.

  11. Highly efficient, widely tunable, 10-Hz parametric amplifier pumped by frequency-doubled femtosecond Ti:sapphire laser pulses.

    PubMed

    Zhang, J Y; Xu, Z; Kong, Y; Yu, C; Wu, Y

    1998-05-20

    We report a 10-Hz, highly efficient, widely tunable (from the visible to the IR), broadband femtosecond optical parametric generator and optical parametric amplifier (OPA) in BBO, LBO, and CBO crystals pumped by the frequency-doubled output of a regeneratively amplified Ti:sapphire laser at 400 nm. The output of the system is continuously tunable from 440 nm to 2.5 microm with a maximum overall efficiency of approximately 25% at 670 nm and an optical conversion efficiency of more than 36% in the OPA stage. The effects of the seed beam energy, the type of the crystal and the crystal length, and the pumping energy of the output of the OPA, such as the optical efficiency, the bandwidth, the pulse duration, and the group velocity mismatch between the signal and the idler and between the seeder and the pump, are investigated. The results provide useful information for optimization of the design of the system. PMID:18273287

  12. Occupational and residential 60-Hz electromagnetic fields and high-frequency electric transients: exposure assessment using a new dosimeter.

    PubMed

    Deadman, J E; Camus, M; Armstrong, B G; Héroux, P; Cyr, D; Plante, M; Thériault, G

    1988-08-01

    One problem that has limited past epidemiologic studies of cancer and exposure to extremely low-frequency (0-100 Hz) electric and magnetic fields has been the lack of adequate methods for assessing personal exposure to these fields. A new 60-Hz electromagnetic field dosimeter was tested to assess occupational and residential exposures of a group of electrical utility workers and a comparison background group over a 7-day period. Comparing work periods only, utility workers' exposures were significantly higher than background levels by a factor of about 10 for electric (E) and magnetic (B) fields and by a factor of 171 for high-frequency transient electric (HFTE) fields. When overall weekly time-weighted averages combining work and nonwork exposures were compared, ratios of the exposed to background groups were lower. B and HFTE exposure ratios remained statistically significant, with values of 3.5 and 58, respectively, whereas the electric field exposure ratio was no longer significant, with a value of 1.7. E-field exposures of the background group were the highest during the nonwork period, probably reflecting the use of electrical appliances at home. Residential E- and B-field exposures were in the same range as published results from other surveys, whereas occupational E-field exposures tended to be lower than exposures reported in other studies. The high variability associated with occupational exposures probably accounts for the latter discrepancy. Worker acceptance of wearing the dosimeter was good: 95% of participants found it to be of little or no inconvenience while at work. At home, 37% found the device to be inconvenient in its present form but would not object to wearing a slightly smaller and lighter dosimeter.

  13. Modification of S. cerevisiae Growth Dynamics Using Low Frequency Electromagnetic Fields in the 1-2 kHz Range

    PubMed Central

    Barabáš, Ján; Radil, Roman; Malíková, Ivona

    2015-01-01

    This paper details our further experiments pertaining to the influence of low frequency electromagnetic fields (LF EMF) on the growth dynamics of two wild-type Saccharomyces cerevisiae strands. We opted to explore frequencies beyond the usual 50–60 Hz range, motivated by the ion parametric resonance theory and several studies which discovered and recorded endogenous biosignals in various Saccharomyces cerevisiae strands in the 0.4–2.0 kHz frequency range, most probably stemming from microtubules. Both yeast strands used in our experiments have been subjected to continuous 66-hour session of LF EMF exposure (frequencies 1.2, 1.4, 1.6, 1.8, and 2.0 kHz; average magnetic flux density 2.43 mT) under identical ambient conditions. Experiment results indicate a frequency-dependent proliferative response of both yeast strands. PMID:26290871

  14. Tunable two-mode Cr{sup 2+} : ZnSe laser with a frequency-noise spectral density of 0.03 Hz Hz{sup -1/2}

    SciTech Connect

    Gubin, Mikhail A; Kireev, A N; Kozlovskii, Vladimir I; Korostelin, Yurii V; Pnev, A B; Podmar'kov, Yu P; Tyurikov, D A; Frolov, M P; Shelestov, D A; Shelkovnikov, Aleksandr S

    2012-06-30

    An optically pumped cw laser on a Cr{sup 2+} : ZnSe crystal with a tunable (in the range of 2.3 - 2 .6 mm) wavelength, operating with generation of two axial modes, has been developed. It is shown that the minimum laser frequency-noise spectral density does not exceed 0.03 Hz Hz{sup -1/2}. Application of this laser in problems of Doppler and Doppler-free spectroscopy makes it possible to detect spectral absorption lines of gases with sensitivities of 5 Multiplication-Sign 10{sup -12} and 2 Multiplication-Sign 10{sup -10} cm{sup -1}, respectively (averaging time {tau} = 1 s). Having stabilised this laser with respect to the Doppler-free resonances of saturated dispersion of methane molecule, one can obtain a short-term frequency stability of 10{sup -15} - 10{sup -16} ({tau} = 1 s).

  15. Slow modulations of high-frequency activity (40-140-Hz) discriminate preictal changes in human focal epilepsy.

    PubMed

    Alvarado-Rojas, C; Valderrama, M; Fouad-Ahmed, A; Feldwisch-Drentrup, H; Ihle, M; Teixeira, C A; Sales, F; Schulze-Bonhage, A; Adam, C; Dourado, A; Charpier, S; Navarro, V; Le Van Quyen, M

    2014-01-01

    Recent evidence suggests that some seizures are preceded by preictal changes that start from minutes to hours before an ictal event. Nevertheless an adequate statistical evaluation in a large database of continuous multiday recordings is still missing. Here, we investigated the existence of preictal changes in long-term intracranial recordings from 53 patients with intractable partial epilepsy (in total 531 days and 558 clinical seizures). We describe a measure of brain excitability based on the slow modulation of high-frequency gamma activities (40-140 Hz) in ensembles of intracranial contacts. In prospective tests, we found that this index identified preictal changes at levels above chance in 13.2% of the patients (7/53), suggesting that results may be significant for the whole group (p < 0.05). These results provide a demonstration that preictal states can be detected prospectively from EEG data. They advance understanding of the network dynamics leading to seizure and may help develop novel seizure prediction algorithms. PMID:24686330

  16. Measurements of seismic wave attenuation for frequencies between 0.1 and 100 Hz in a Paterson Rig

    NASA Astrophysics Data System (ADS)

    Madonna, C.; Tisato, N.; Delle Piane, C.; Saenger, E. H.

    2012-04-01

    The study of wave attenuation in partially saturated porous rocks over a broad frequency range provides valuable information about reservoir fluid systems, which are inherently composed of multiple phase fluid. Following an original idea initiated by Luigi, we designed and set up a specific instrument, the Seismic Wave Attenuation Module (SWAM), to experimentally measure the bulk attenuation on partially saturated rocks at frequencies between 0.01 and 100 Hz, using natural rock samples under in situ conditions. We present its bench-top calibration, a series of data collected from different kind of rocks at different confing pressure and the numerical simulations, supporting the obtained results. We employ the sub-resonance test. Assuming that the rock behaves as a linear time invariant (LTI) system, the attenuation factor 1/Q (Q is the quality factor) is equal to the tangent of the phase shift between the stress and the strain signal. The new attenuation measurement equipment is calibrated in a gas apparatus (Paterson rig) using aluminum as elastic standard and Plexiglas as a viscoelastic standard. Measurements were performed on 25.4 mm diameter, 60 mm long samples. Berea sandstone samples with 20% porosity, and ~500 mD permeability have been measured at different saturation conditions. Attenuation measurements show dependence upon saturation. Moreover, measurements on two well-characterized shale samples have been performed. The two shales have significantly different quality factors; which result to be dependent on both the saturation state of the samples and the propagation direction of the oscillatory signal with respect to the sedimentary bedding. The attenuation coefficient parallel to bedding is less than that vertical to bedding. Thanks to Luigi's initiative and inspiration two generations of his Ph.D. students are now able to jointly present these new challenging experimental results.

  17. Studies of selective attention in dogs using the coherence-phase characteristics of cortical potentials over a wide range of frequencies, 1-220 Hz.

    PubMed

    Dumenko, V N; Kozlov, M K

    2003-07-01

    The state of selective attention formed during operant food-related behavior was studied using the coherence-phase characteristics between potentials in several areas of the neocortex at frequencies of 1-220 Hz. Functional groups were identified among the areas compared, which appear to have priority for this state. The temporal relationships between potentials in these groups were established from values for coherence functions at a particular optimum level (0.7) mainly in the band 1-15 Hz and the high-frequency range 40-200 Hz. The phenomenon of synchronicity appeared at phase shifts close to zero, while at significant phase shifts the phenomenon of non-synchronous time relationships with defined spatial directions was seen in the high-frequency range.

  18. Flexural composite oscillators for the measurement of anelastic and elastic properties of solids at frequencies of 1 to 10 kHz.

    PubMed

    Devine, S D; Robinson, W H

    1998-01-01

    Longitudinal composite oscillators for measuring internal friction, piezoelectric modulus, and strain modulation effects are usually limited to a frequency range of 30 to 200 kHz. If the same crystals are vibrated in flexure, a longitudinal strain can be introduced with the resonance frequency below 3 kHz while at the same time keeping the inherent high Q of the composite system. This paper develops the theory for the strain amplitude and damping for the flexural composite oscillator made up of two quartz crystals plus specimen and, if appropriate, spacers. This high Q technique of vibrating in flexure has applications for strain modulation and damping experiments. PMID:18244153

  19. Studies of selective attention in dogs using the energy characteristics of neocortical potentials in the frequency range 1-220 Hz.

    PubMed

    Dumenko, V N; Kozlov, M L; Kulikov, M A

    2002-01-01

    Experiments were performed in dogs to study the state of selective attention formed during operant food-related training and apparent during interstimulus intervals as a state of tense expectation of the conditioned signal. Electrical activity in various parts of the neocortex, in both hemispheres, was analyzed in the frequency range 1-220 Hz (epidural electrodes) using Fourier transforms. The electrical activity of the motor area of the right hemisphere showed a predominance of high-frequency (40-200 Hz) components, as did the visual and parietal areas of the left hemisphere. The state of selective attention was associated with a different functional mosaic in the organization of neocortical electrical activity.

  20. Domain self-organization in iron garnet films in pulsed magnetic fields with a frequency between 0.001 and 25 Hz

    NASA Astrophysics Data System (ADS)

    Osadchenko, V. Kh.; Kandaurova, G. S.; Pashko, A. G.

    2007-04-01

    The results of studying processes of self-organization in a domain structure of highly anisotropic iron garnet films with perpendicular anisotropy in an ac magnetic field of a symmetrical meander type (with rectangular pulses with a frequency of 0.001-25 Hz and an amplitude H 0 = 0-70 Oe are reported for the first time. In the frequency range from 0.01 to 25 Hz, there has been observed an anger (excited) state, which is characterized by the formation of a close packing of spiral dynamic domains.

  1. Welding characteristics of 27, 40 and 67 kHz ultrasonic plastic welding systems using fundamental- and higher-resonance frequencies.

    PubMed

    Tsujino, Jiromaru; Hongoh, Misugi; Yoshikuni, Masafumi; Hashii, Hidekazu; Ueoka, Tetsugi

    2004-04-01

    The welding characteristics of 27, 40 and 67 kHz ultrasonic plastic welding systems that are driven at only the fundamental-resonance frequency vibration were compared, and also those of the welding systems that were driven at the fundamental and several higher resonance frequencies simultaneously were studied. At high frequency, welding characteristics can be improved due to the larger vibration loss of plastic materials. For welding of rather thin or small specimens, as the fundamental frequency of these welding systems is higher and the numbers of driven higher frequencies are driven simultaneously, larger welded area and weld strength were obtained.

  2. Final report of supplementary comparison AFRIMETS.AUV.A-S1: primary pressure calibration of LS2aP microphones according to IEC 61094-2, over the frequency range 1 Hz to 31.5 kHz.

    NASA Astrophysics Data System (ADS)

    Nel, R.; Barrera-Figueroa, S.; Dobrowolska, D.; Defilippo Soares, Z. M.; Maina, A. K.; Hof, C.

    2016-01-01

    This is the final report of the AFRIMETS.AUV-S1 comparison of the pressure sensitivity, modulus and phase, of LS2aP microphones in the frequency range 1 Hz to 31.5 kHz in accordance with IEC 61094-2. Six national metrology institutes from three different regional metrology organisations participated in the comparison for which two LS2aP microphones were circulated simultaneously to all the participants in a hybrid-star configuration. The comparison reference values were calculated as the weighted mean for modulus and phase for each individual microphone. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCAUV, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  3. Polarization behavior of polystyrene particles under direct current and low-frequency (<1 kHz) electric fields in dielectrophoretic systems.

    PubMed

    Saucedo-Espinosa, Mario A; Rauch, Mallory M; LaLonde, Alexandra; Lapizco-Encinas, Blanca H

    2016-02-01

    The relative polarization behavior of micron and submicron polystyrene particles was investigated under direct current and very low frequency (<1 kHz) alternating current electric fields. Relative polarization of particles with respect to the suspending medium is expressed in terms of the Clausius-Mossotti factor, a parameter of crucial importance in dielectrophoretic-based operations. Particle relative polarization was studied by employing insulator-based dielectrophoretic (iDEP) devices. The effects of particle size, medium conductivity, and frequency (10-1000 Hz) of the applied electric potential on particle response were assessed through experiments and mathematical modeling with COMSOL Multiphysics(®). Particles of different sizes (100-1000 nm diameters) were introduced into iDEP devices fabricated from polydimethylsiloxane (PDMS) and their dielectrophoretic responses under direct and alternating current electric fields were recorded and analyzed in the form of images and videos. The results illustrated that particle polarizability and dielectrophoretic response depend greatly on particle size and the frequency of the electric field. Small particles tend to exhibit positive DEP at higher frequencies (200-1000 Hz), while large particles exhibit negative DEP at lower frequencies (20-200 Hz). These differences in relative polarization can be used for the design of iDEP-based separations and analysis of particle mixtures.

  4. Polarization behavior of polystyrene particles under direct current and low-frequency (<1 kHz) electric fields in dielectrophoretic systems.

    PubMed

    Saucedo-Espinosa, Mario A; Rauch, Mallory M; LaLonde, Alexandra; Lapizco-Encinas, Blanca H

    2016-02-01

    The relative polarization behavior of micron and submicron polystyrene particles was investigated under direct current and very low frequency (<1 kHz) alternating current electric fields. Relative polarization of particles with respect to the suspending medium is expressed in terms of the Clausius-Mossotti factor, a parameter of crucial importance in dielectrophoretic-based operations. Particle relative polarization was studied by employing insulator-based dielectrophoretic (iDEP) devices. The effects of particle size, medium conductivity, and frequency (10-1000 Hz) of the applied electric potential on particle response were assessed through experiments and mathematical modeling with COMSOL Multiphysics(®). Particles of different sizes (100-1000 nm diameters) were introduced into iDEP devices fabricated from polydimethylsiloxane (PDMS) and their dielectrophoretic responses under direct and alternating current electric fields were recorded and analyzed in the form of images and videos. The results illustrated that particle polarizability and dielectrophoretic response depend greatly on particle size and the frequency of the electric field. Small particles tend to exhibit positive DEP at higher frequencies (200-1000 Hz), while large particles exhibit negative DEP at lower frequencies (20-200 Hz). These differences in relative polarization can be used for the design of iDEP-based separations and analysis of particle mixtures. PMID:26531799

  5. Transposed stimuli improve sensitivity to envelope-based interaural timing information for stimuli having center frequencies of up to 10 kHz

    NASA Astrophysics Data System (ADS)

    Bernstein, Leslie R.; Trahiotis, Constantine

    2002-05-01

    Threshold interaural temporal disparities (ITDs) at high frequencies are larger than threshold ITDs obtained at low frequencies. Colburn and Esquissaud [J. Acoust. Soc. Am. Suppl. 1 59, S23 (1976)], hypothesized that this reflects differences in peripheral processing of the stimuli rather than in binaural mechanisms that mediate performance. Previously [L. R. Bernstein and C. Trahiotis, J. Acoust. Soc. Am. 109, 2485 (2001)] this hypothesis was supported in ITD-discrimination experiments employing high-frequency ``transposed stimuli'' centered at 4 kHz that were designed to provide high-frequency channels with envelope-based information mimicking that normally available only in low-frequency channels. Here, we report new results using stimuli centered at 4, 6, and 10 kHz. It was found that (1) transposed stimuli can yield relatively small threshold ITDs, even at 6 and 10 kHz, (2) the data could be well accounted for in terms of a constant-criterion change in normalized interaural correlation computed subsequent to bandpass filtering, compression, rectification, and low-pass filtering. In addition, it was found necessary to incorporate a specific limitation to capture the inability of the auditory system to follow envelope fluctuations greater than 150 Hz. [Work supported by NIH DC 04147.

  6. 295 mW output, frequency-stabilized erbium silica fiber laser with a linewidth of 5 kHz and a RIN of -120 dB/Hz.

    PubMed

    Kasai, Keisuke; Yoshida, Masato; Nakazawa, Masataka

    2016-02-01

    We demonstrate the frequency stabilization of a high output power, erbium silica fiber laser by utilizing a (13)C2H2 (acetylene) absorption line at 1538.8 nm and a H(13)C(14)N (hydrogen cyanide) absorption line at 1549.73 nm. We introduced a novel short ring cavity configuration and pump power feedback control to suppress the intensity noise of the laser output, which is caused by the relaxation oscillation of erbium ions. As a result, we succeeded in simultaneously obtaining a stable single-frequency oscillation with an output power of over 290 mW, a linewidth of 5 kHz, and a low relative intensity noise (RIN) of -120 dB/Hz. The frequency stabilities reached 2.8 × 10(-11) and 6.9 × 10(-11) for an integration time of 1 s with a (13)C2H2 and a H(13)C(14)N absorption line, respectively.

  7. Investigation of the lasing characteristics of a barium vapor laser with pulse repetition frequencies up to 320 kHz for navigation

    NASA Astrophysics Data System (ADS)

    Soldatov, A. N.; Polunin, Yu. P.

    2015-11-01

    Results of experimental investigations into the characteristics of a laser on self-terminating transitions of the barium atom with λ = 1499 nm are presented for high pulse repetition frequencies (PRF). The frequency-energy characteristics are investigated in the self-heating mode of laser operation. Record values of PRF for the barium vapor laser, equal to ~320 kHz, have been attained.

  8. Active frequency stabilization of a 1.062-micron, Nd:GGG, diode-laser-pumped nonplanar ring oscillator to less than 3 Hz of relative linewidth

    NASA Technical Reports Server (NTRS)

    Day, T.; Gustafson, E. K.; Byer, R. L.

    1990-01-01

    Results are presented on the frequency stabilization of two diode-laser-pumped ring lasers that are independently locked to the same high-finesse interferometer. The relative frequency stability is measured by locking the lasers one free spectral range apart and observing the heterodyne beat note. The resultant beat note width of 2.9 Hz is consistent with the theoretical system noise-limited linewidth and is approximately 20 times that expected for shot-noise-limited performance.

  9. The power-law and linear correlations between the twin kHz QPO frequencies in LMXBs

    NASA Astrophysics Data System (ADS)

    Yin, H. X.; Zhao, Y. H.

    After the launch of the Rossi X-ray Timing Explorer RXTE our knowledge of the aperiodic variability of newtron star NS low mass X-ray binaries LMXBs took a substantial step forward especially initiated by the discovery of the kilohertz quasi-periodic oscillations kHz QPOs in about twenty more NS LMXBs We analyzed the recently updated kHz QPO data in NS LMXBs in order to investigate the different correlations of the twin peak kilohertz quasi-periodic oscillations kHz QPOs in bright Z sources and in the less luminous Atoll sources We fitted the data with a power-law relation nu 1 sim nu 2 b and a linear relation nu 2 sim A nu 1 between the upper and the lower kHz QPOs and find that both relations can fit the data well with small chi 2 values sim 1 The implications of our results for the theoretical models for kHz QPOs are discussed

  10. Safety considerations for magnetic fields of 10 mT to 100 mT amplitude in the frequency range of 10 kHz to 100 kHz for magnetic particle imaging.

    PubMed

    Dössel, Olaf; Bohnert, Julia

    2013-12-01

    Magnetic particle imaging (MPI) is a new imaging modality using oscillating magnetic fields in the frequency range of 10 kHz to 100 kHz. The duration of data acquisition becomes smaller, and signal-to-noise ratio improves if the amplitude of these fields is increased - technically amplitudes of up to 100 mT might be feasible for human-sized systems. On the other hand, with increasing field strength, adverse health effects must be expected: oscillating magnetic fields can stimulate nerves and muscle and heat up tissue. Thresholds for stimulation with magnetic fields in this frequency range are not precisely known, neither is the local temperature rise following exposure. The ICNIRP guidelines define reference levels for magnetic field exposure for the general public that contain large safety factors - for medical diagnostics, they might be exceeded for a short time. In this article, research and guidelines in this field are briefly reviewed, and new results are presented in order to contribute to a future definition of safety limits for oscillating magnetic fields in MPI. PMID:24176960

  11. Safety considerations for magnetic fields of 10 mT to 100 mT amplitude in the frequency range of 10 kHz to 100 kHz for magnetic particle imaging.

    PubMed

    Dössel, Olaf; Bohnert, Julia

    2013-12-01

    Magnetic particle imaging (MPI) is a new imaging modality using oscillating magnetic fields in the frequency range of 10 kHz to 100 kHz. The duration of data acquisition becomes smaller, and signal-to-noise ratio improves if the amplitude of these fields is increased - technically amplitudes of up to 100 mT might be feasible for human-sized systems. On the other hand, with increasing field strength, adverse health effects must be expected: oscillating magnetic fields can stimulate nerves and muscle and heat up tissue. Thresholds for stimulation with magnetic fields in this frequency range are not precisely known, neither is the local temperature rise following exposure. The ICNIRP guidelines define reference levels for magnetic field exposure for the general public that contain large safety factors - for medical diagnostics, they might be exceeded for a short time. In this article, research and guidelines in this field are briefly reviewed, and new results are presented in order to contribute to a future definition of safety limits for oscillating magnetic fields in MPI.

  12. LOW-FREQUENCY (11 mHz) OSCILLATIONS IN H1743-322: A NEW CLASS OF BLACK HOLE QUASI-PERIODIC OSCILLATIONS?

    SciTech Connect

    Altamirano, D.; Strohmayer, T.

    2012-08-01

    We report the discovery of quasi-periodic oscillations (QPOs) at {approx}11 mHz in two RXTE and one Chandra observations of the black hole candidate H1743-322. The QPO is observed only at the beginning of the 2010 and 2011 outbursts at similar hard color and intensity, suggestive of an accretion state dependence for the QPO. Although its frequency appears to be correlated with X-ray intensity on timescales of a day, in successive outbursts eight months apart, we measure a QPO frequency that differs by less than Almost-Equal-To 2.2 mHz while the intensity had changed significantly. We show that this {approx}11 mHz QPO is different from the so-called Type C QPOs seen in black holes and that the mechanisms that produce the two flavors of variability are most probably independent. After comparing this QPO with other variability phenomena seen in accreting black holes and neutron stars, we conclude that it best resembles the so-called 1 Hz QPOs seen in dipping neutron star systems, although having a significantly lower (1-2 orders of magnitude) frequency. If confirmed, H1743-322 is the first black hole showing this type of variability. Given the unusual characteristics and the hard-state dependence of the {approx}11 mHz QPO, we also speculate whether these oscillations could instead be related to the radio jets observed in H1743-322. A systematic search for this type of low-frequency QPOs in similar systems is needed to test this speculation. In any case, it remains unexplained why these QPOs have only been seen in the last two outbursts of H1743-322.

  13. Alcohol enhances unprovoked 22-28 kHz USVs and suppresses USV mean frequency in High Alcohol Drinking (HAD-1) male rats.

    PubMed

    Thakore, Neha; Reno, James M; Gonzales, Rueben A; Schallert, Timothy; Bell, Richard L; Maddox, W Todd; Duvauchelle, Christine L

    2016-04-01

    Heightened emotional states increase impulsive behaviors such as excessive ethanol consumption in humans. Though positive and negative affective states in rodents can be monitored in real-time through ultrasonic vocalization (USV) emissions, few animal studies have focused on the role of emotional status as a stimulus for initial ethanol drinking. Our laboratory has recently developed reliable, high-speed analysis techniques to compile USV data during multiple-hour drinking sessions. Since High Alcohol Drinking (HAD-1) rats are selectively bred to voluntarily consume intoxicating levels of alcohol, we hypothesized that USVs emitted by HAD-1 rats would reveal unique emotional phenotypes predictive of alcohol intake and sensitive to alcohol experience. In this study, male HAD-1 rats had access to water, 15% and 30% EtOH or water only (i.e., Controls) during 8 weeks of daily 7-h drinking-in-the-dark (DID) sessions. USVs, associated with both positive (i.e., 50-55 kHz frequency-modulated or FM) and negative (i.e., 22-28 kHz) emotional states, emitted during these daily DID sessions were examined. Findings showed basal 22-28 kHz USVs were emitted by both EtOH-Naïve (Control) and EtOH-experienced rats, alcohol experience enhanced 22-28 kHz USV emissions, and USV acoustic parameters (i.e., mean frequency in kHz) of both positive and negative USVs were significantly suppressed by chronic alcohol experience. These data suggest that negative affective status initiates and maintains excessive alcohol intake in selectively bred HAD-1 rats and support the notion that unprovoked emissions of negative affect-associated USVs (i.e., 22-28 kHz) predict vulnerability to excessive alcohol intake in distinct rodent models. PMID:26802730

  14. Alcohol enhances unprovoked 22-28 kHz USVs and suppresses USV mean frequency in High Alcohol Drinking (HAD-1) male rats.

    PubMed

    Thakore, Neha; Reno, James M; Gonzales, Rueben A; Schallert, Timothy; Bell, Richard L; Maddox, W Todd; Duvauchelle, Christine L

    2016-04-01

    Heightened emotional states increase impulsive behaviors such as excessive ethanol consumption in humans. Though positive and negative affective states in rodents can be monitored in real-time through ultrasonic vocalization (USV) emissions, few animal studies have focused on the role of emotional status as a stimulus for initial ethanol drinking. Our laboratory has recently developed reliable, high-speed analysis techniques to compile USV data during multiple-hour drinking sessions. Since High Alcohol Drinking (HAD-1) rats are selectively bred to voluntarily consume intoxicating levels of alcohol, we hypothesized that USVs emitted by HAD-1 rats would reveal unique emotional phenotypes predictive of alcohol intake and sensitive to alcohol experience. In this study, male HAD-1 rats had access to water, 15% and 30% EtOH or water only (i.e., Controls) during 8 weeks of daily 7-h drinking-in-the-dark (DID) sessions. USVs, associated with both positive (i.e., 50-55 kHz frequency-modulated or FM) and negative (i.e., 22-28 kHz) emotional states, emitted during these daily DID sessions were examined. Findings showed basal 22-28 kHz USVs were emitted by both EtOH-Naïve (Control) and EtOH-experienced rats, alcohol experience enhanced 22-28 kHz USV emissions, and USV acoustic parameters (i.e., mean frequency in kHz) of both positive and negative USVs were significantly suppressed by chronic alcohol experience. These data suggest that negative affective status initiates and maintains excessive alcohol intake in selectively bred HAD-1 rats and support the notion that unprovoked emissions of negative affect-associated USVs (i.e., 22-28 kHz) predict vulnerability to excessive alcohol intake in distinct rodent models.

  15. 15 CFR 10.12 - Editorial changes.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 15 Commerce and Foreign Trade 1 2011-01-01 2011-01-01 false Editorial changes. 10.12 Section 10.12... PRODUCT STANDARDS § 10.12 Editorial changes. The Department may, without prior notice, make such editorial or other minor changes as it deems necessary to reduce ambiguity or to improve clarity in...

  16. 15 CFR 10.12 - Editorial changes.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 15 Commerce and Foreign Trade 1 2010-01-01 2010-01-01 false Editorial changes. 10.12 Section 10.12... PRODUCT STANDARDS § 10.12 Editorial changes. The Department may, without prior notice, make such editorial or other minor changes as it deems necessary to reduce ambiguity or to improve clarity in...

  17. Effect of non-symmetric waveform on conduction block induced by high-frequency (kHz) biphasic stimulation in unmyelinated axon.

    PubMed

    Zhao, Shouguo; Yang, Guangning; Wang, Jicheng; Roppolo, James R; de Groat, William C; Tai, Changfeng

    2014-10-01

    The effect of a non-symmetric waveform on nerve conduction block induced by high-frequency biphasic stimulation is investigated using a lumped circuit model of the unmyelinated axon based on Hodgkin-Huxley equations. The simulation results reveal that the block threshold monotonically increases with the stimulation frequency for the symmetric stimulation waveform. However, a non-monotonic relationship between block threshold and stimulation frequency is observed when the stimulation waveform is non-symmetric. Constant activation of potassium channels by the high-frequency stimulation results in the increase of block threshold with increasing frequency. The non-symmetric waveform with a positive pulse 0.4-0.8 μs longer than the negative pulse blocks axonal conduction by hyperpolarizing the membrane and causes a decrease in block threshold as the frequency increases above 12-16 kHz. On the other hand, the non-symmetric waveform with a negative pulse 0.4-0.8 μs longer than the positive pulse blocks axonal conduction by depolarizing the membrane and causes a decrease in block threshold as the frequency increases above 40-53 kHz. This simulation study is important for understanding the potential mechanisms underlying the nerve block observed in animal studies, and may also help to design new animal experiments to further improve the nerve block method for clinical applications.

  18. Energy dependence of r.m.s amplitude of low frequency broadband noise and kHz quasi periodic oscillations in 4U 1608-52

    NASA Astrophysics Data System (ADS)

    Mandal, Soma

    2016-07-01

    The neutron star low mass X-ray binary 4U 1608-52 is known to show kHz QPOs as well as low frequency broad band noise. The energy dependence of the fractional r.m.s of these variations reflect the underlying radiative mechanism responsible for the phenomena. In this work we compute the energy depedence for 26 instances of kHz QPO observed by RXTE. We typically find as reported before, that the r.m.s increases with energy with slope of ˜0.5. This indicates that the variation is in the hot thermal compotonization component and in particular the QPO is likely to be driven by variation in the thermal heating rate of the hot plasma. For the same data, we compute the energy dependent r.m.s variability of the low frequency broad band noise component by considering the light curves. In contrast to the behaviour seen for the kHz QPO, the energy dependence is nearly flat i.e. the r.m.s. is energy independent. This indicates that the driver here may be the soft photon source. Thus the radiative mechanism driving the low frequency broad band noise and the high frequency QPO are different in nature.

  19. Effects of time varying currents and magnetic fields in the frequency range of 1 kHz to 1 MHz to the human body - a simulation study.

    PubMed

    Bohnert, Julia; Dössel, Olaf

    2010-01-01

    Exposure to time-varying magnetic fields evokes two effects in biological tissue: Firstly, an electric field is induced that generates eddy currents in conductive tissues, and, secondly, power deposit might increase local temperatures. Field effects of frequencies up to 1 kHz and above 1 MHz are well known. The intermediate frequency range lacks intensive research. Only little attention has been paid so far. Yet due to recent innovations in medical diagnostics and therapies like Magnetic Particle Imaging or RF-Hyperthermia, the need arises to investigate the frequency range from 1kHz to 1 MHz. This work presents results of numerical field calculations of a human body model placed within simple coil configurations. Induced current densities, generated by alternating coil currents, are simulated. The effect of current densities are demonstrated and evaluated on schematic cell models of excitable tissue. In order to generate an action potential at the cell membrane, a difference in electric potential from intra- to extracellular space must be present. It can be shown that in case of sufficient field strength, stimulation of nerves and muscles is possible up to a frequency of 100 kHz. The aim of this paper is to transfer simulation results from the macroscopic model to the microscopic model in order to estimate field effects of big field generating coils.

  20. [Efficacy of dynamic magnetotherapy with modulation frequency 10Hz in the complex of spa rehabilitation of children with cerebral palsy].

    PubMed

    Gurova, N Iu; Babina, L M

    2007-01-01

    Two groups of children with cerebral paralysis received combined therapy. Treatment of one of the groups included a course of magnetotherapy (AMO-ATOS unit, 10 Hz) according to the suboccipital-lumbar method, the other group was control (no magnetotherapy). The study of cliniconeurophysiological indices showed significantly higher efficacy of the therapeutic complex with a course of magnetotherapy. The highest beneficial effect was observed on bioelectrogenesis of the brain, rheoencephalographic parameters and clinical manifestation of muscular spasticity. PMID:17886367

  1. Afferent inputs to cortical fast-spiking interneurons organize pyramidal cell network oscillations at high-gamma frequencies (60-200 Hz).

    PubMed

    Suffczynski, Piotr; Crone, Nathan E; Franaszczuk, Piotr J

    2014-12-01

    High-gamma activity, ranging in frequency between ∼60 Hz and 200 Hz, has been observed in local field potential, electrocorticography, EEG and magnetoencephalography signals during cortical activation, in a variety of functional brain systems. The origin of these signals is yet unknown. Using computational modeling, we show that a cortical network model receiving thalamic input generates high-gamma responses comparable to those observed in local field potential recorded in monkey somatosensory cortex during vibrotactile stimulation. These high-gamma oscillations appear to be mediated mostly by an excited population of inhibitory fast-spiking interneurons firing at high-gamma frequencies and pacing excitatory regular-spiking pyramidal cells, which fire at lower rates but in phase with the population rhythm. The physiological correlates of high-gamma activity, in this model of local cortical circuits, appear to be similar to those proposed for hippocampal ripples generated by subsets of interneurons that regulate the discharge of principal cells. PMID:25210164

  2. Calibration of miniature medical ultrasonic hydrophones for frequencies in the range 100 to 500 kHz using an ultrasonically absorbing waveguide.

    PubMed

    Rajagopal, Srinath; Zeqiri, Bajram; Gélat, Pierre N

    2014-05-01

    Enhancements to the existing primary standard optical interferometer and narrowband tone-burst comparison calibration methods for miniature medical ultrasonic hydrophones of the membrane type over the frequency range 100 to 500 kHz are described. Improvements were realized through application of an ultrasonically absorbing waveguide made of a low-frequency-absorbing tile used in sonar applications which narrows the spatial extent of the broad acoustic field. The waveguide was employed in conjunction with a sonar multilayered polyvinylidene difluoride (PVDF) hydrophone used as a transmitting transducer covering a frequency range of 100 kHz to 1 MHz. The acoustic field emanating from the ultrasonically absorbing waveguide reduced the significance of diffracted acoustic waves from the membrane hydrophone ring and the consequent interference of this wave with the direct acoustic wave received by the active element of the hydrophone during calibration. Four membrane hydrophone make/ models with ring sizes (defined as the inner diameter of the annular mounting ring of the hydrophone) in the range 50 to 100 mm were employed along with a needle hydrophone. A reference membrane hydrophone, calibrated using the NPL primary standard optical interferometer in combination with the ultrasonically absorbing waveguide, was subsequently used to calibrate the other four hydrophones by comparison, again using the ultrasonically absorbing waveguide. In comparison to existing methods, the use of the ultrasonically absorbing waveguide enabled the low-frequency calibration limit of a membrane hydrophone with a ring diameter of 50 mm to be reduced from 400 kHz to 200 kHz.

  3. Impedance of Aqueous Solutions of KCl at the Ultra-low Frequency Range: Use of Cole-Cole Impedance Element to Account for the Frequency Dispersion Peak at 20 mHz

    NASA Astrophysics Data System (ADS)

    Giacometti, José A.; Alves, Neri; Teruya, Márcia Y.

    2016-02-01

    This paper reports on the analysis of dispersion in the imaginary part of impedance often observed at low frequencies in a variety of systems. The experimental data were obtained with an electrolytic cell containing KCl aqueous solution in the frequency range from 0.1 mHz to 10 MHz, where the use of ultra-low frequencies helps clarify the analysis of the imaginary impedance dispersion. It is shown that the low frequency dispersion described in the literature is the tail of a relaxation peak located at f ≅ 20 mHz. This ultra-low frequency dispersion peak is analyzed with a Cole-Cole impedance element, being associated with the electric double layer at the metal-electrolyte interface. Quantitative information can be extracted for the double layer, including its thickness (˜1 nm) and electrical resistivity (˜50 GΩm).

  4. Attenuation of High-Frequency (50-200 Hz) Thalamocortical EEG Rhythms by Propofol in Rats Is More Pronounced for the Thalamus than for the Cortex

    PubMed Central

    Reed, Sean J.; Plourde, Gilles

    2015-01-01

    Background Thalamocortical EEG rhythms in gamma (30-80 Hz) and high-gamma (80-200 Hz) ranges have been linked to arousal and conscious processes. To test the hypothesis that general anesthetics attenuate these rhythms, we characterized the concentration-effect relationship of propofol on the spectral power of these rhythms. In view of the ongoing debate about cortex versus thalamus as the primary site of anesthetic action for unconsciousness, we also compared the relative sensitivity of cortex and thalamus to this effect propofol. Methods Adult male Long-Evans rats were chronically implanted with electrodes in somatosensory (barrel) cortex and ventroposteromedial thalamus. Propofol was delivered by a computer-controlled infusion using real-time pharmacokinetic modeling to obtain the desired plasma concentration. Spectral power was assessed during baseline, at four stable propofol plasma-concentrations (0, 3,6,9,12 μg/ml) and during recovery over four frequency ranges (30-50, 51-75, 76-125, 126-200 Hz). Unconsciousness was defined as complete loss of righting reflex. Multiple regression was used to model the change of power (after logarithmic transformation) as a function of propofol concentration and recording site. Results Unconsciousness occurred at the 9 μg/ml concentration in all animals. Propofol caused a robust linear concentration-dependent attenuation of cortical power in the 76-200 Hz range and of thalamic power in the 51-200 Hz range. In all instances the concentration-effect slope for the thalamus was markedly steeper than for the cortex. Furthermore the lowest concentration causing unconsciousness significantly reduced cortical power in the 126-200 Hz range and thalamic power in the 51-200 Hz range. Conclusions Propofol causes a concentration-dependent attenuation of the power of thalamocortical rhythms in the 51-200 Hz range and this effect is far more pronounced for the thalamus, where the attenuation provides a robust correlate of the hypnotic

  5. A spectral-timing analysis of the kHz QPOs in 4U 1636-53: the frequency-energy resolved RMS spectrum

    NASA Astrophysics Data System (ADS)

    Ribeiro, Evandro M.; Mendez, Mariano; Zhang, Guo-Bao; De Avellar, Márcio G. B.

    2016-07-01

    Our understanding of quasi-periodic oscillations (QPO) has been further advanced in the last few years by the use of combined spectral and timing techniques, and it is now clear that QPO properties are closely related to the spectral state of the source in which they appear. In this work we used all the available RXTE observations of the neutron-star low-mass X-ray binary 4U~1636-53 to study the properties of the kilohertz QPO as a function of energy and frequency. By following the frequency evolution of the kHz QPOs we created frequency-resolved fractional RMS spectra. We also studied the connection between the frequency of the kHz QPOs and the parameters of the model that fits the X-ray energy spectrum. We show the dependence of the QPO properties in a multi-parameter space, and we discuss the implication of our results to the mechanism that produces the QPOs. Our results provide input to the next generation of spectral-timing models, which will help us understand the variability and the environment around the neutron star in these systems.

  6. [Study of selective attention in dogs by coherent-phase characteristics of cortical potentials in the broad frequency band 1-220 Hz].

    PubMed

    Dumenko, V N; Kozlov, M K

    2002-01-01

    Coherent-phase characteristics of cortical potentials (1-220 Hz) derived from different cortical point of both brain hemispheres of dogs were analyzed in the state of selective attention developed in the course of instrumental food conditioning. Among the compared cortical points, functional groups were found that were probably of priority for the state of selective attention. Values of coherence function between these derivations (an assessment of temporal relations) were at a certain optimal level (about 0.7), predominantly, in the frequency ranges of 1-15 and 40-200 Hz. Under such conditions, if the average phase shifts between the potentials were near zero, phenomenon of potential synchronism was formed. In case of significant phase shifts, phenomenon of asynchronous temporal relations with a certain spatial direction developed.

  7. Extremely low frequency 7 Hz 100 microT electromagnetic radiation promotes differentiation in the human epithelial cell line HaCaT.

    PubMed

    Lisi, Antonella; Foletti, Alberto; Ledda, Mario; Rosola, Emanuela; Giuliani, Livio; D'Emilia, Enrico; Grimaldi, Settimio

    2006-01-01

    Electromagnetic therapy is a treatment method in which an electromagnetic or magnetic stimulus is used to achieve physiological changes in the body. The specific aim of the present work concerns the effectiveness of low frequency electromagnetic fields to modify the biochemical properties of human keratinocytes (HaCaT). Cells exposed to a 7 Hz 100 microT electromagnetic field for one hour (twice daily), indicated modification in shape and morphology. These modifications were also associated with different actin distribution as revealed by phalloidin fluorescence analysis. Indirect immunofluorescence with fluorescent antibodies against involucrin and beta-Catenin, both differentiation and adhesion markers, revealed an increase in involucrin and beta-Catenin expression, supporting the conclusion that exposure to electromagnetic field carries keratinocytes to an upper differentiation level. This study confirms our previous observation and supports the hypothesis that 7 Hz electromagnetic field, may modify cell biochemistry interfering in the differentiation and cellular adhesion of normal keratinocytes.

  8. The changes of the frequency specific impedance of the human body due to the resonance in the kHz range in cancer diagnostics

    NASA Astrophysics Data System (ADS)

    Michalak, K. P.; Nawrocka-Bogusz, H.

    2011-12-01

    The frequency-specific absorption of kHz signals has been postulated for different tissues, trace elements, vitamins, toxins, pathogens, allergens etc. for low-power (μV) signals. An increase in the impedance of the human body is observed only up to the given power of the applied signal. The highest amplification of the given signal being damped by the body makes it possible to determine the intensity of the given process in the body (e.g. amount of the toxin, trace element, intensity of the allergy) being connected with a given frequency spectrum of the signal. The mechanism of frequency-specific absorption can be explained by means of the Quantum Field Theory being applied to the structure of the water. Substantially high coincidence between the frequencies of the rotation of free quasi-excited electrons in coherent domains of water and the frequencies being used in the MORA diagnostics (Med-Tronic GmbH, EN ISO 13485, EN ISO 9001) can be observed. These frequencies are located in the proximity of f = 7kHz · i (i = 1,3,5,7,...). This fact suggests that the coherent domains with the admixtures of the given substances create structure-specific coherent domains that possess frequency-specific absorption spectra. The diagnostic tool called "MORA System diagnosis" was used to investigate 102 patients with different types and stages of cancer. Many signals were observed to be absorbed by many cancer patients, e.g.: 'Cellular defense system', 'Degeneration tendencies', Manganese, Magnesium, Zinc, Selenium, Vitamin E, Glutamine, Glutathione, Cysteine, Candida albicans, Mycosis. The results confirm the role of oxidative stress, immunological system deficiency and mitochondria malfunction in the development of cancer.

  9. Investigation of atmospheric insect wing-beat frequencies and iridescence features using a multi-spectral kHz remote detection system

    NASA Astrophysics Data System (ADS)

    Gebru, Alem; Rohwer, Erich; Neethling, Pieter; Brydegaard, Mikkel

    2014-10-01

    Quantitative investigation of insect activity in their natural habitat is a challenging task for entomologist. It is difficult to address questions such as flight direction, predation strength and overall activities using the current techniques such as traps and sweep nets. A multi-spectral kHz remote detection system using sunlight as an illumination source is presented. We explore possibilities of remote optical classification of insects based on their wing-beat frequencies and iridescence features. It is shown that the wing-beat frequency of the fast insect events can be resolved by implementing high sampling frequency. The iridescence features generated from the change of color in two channels (visible and near infrared) during wing-beat cycle is presented. We show that the shape of the wing-beat trajectory is different for different insects. The flight direction of atmospheric insect is also determined using silicon quadrant detector.

  10. Bidirectional modulation of hippocampal gamma (20-80 Hz) frequency activity in vitro via alpha(α)- and beta(β)-adrenergic receptors (AR).

    PubMed

    Haggerty, D C; Glykos, V; Adams, N E; Lebeau, F E N

    2013-12-01

    Noradrenaline (NA) in the hippocampus plays an important role in memory function and has been shown to modulate different forms of synaptic plasticity. Oscillations in the gamma frequency (20-80 Hz) band in the hippocampus have also been proposed to play an important role in memory functions and, evidence from both in vitro and in vivo studies, has suggested this activity can be modulated by NA. However, the role of different NA receptor subtypes in the modulation of gamma frequency activity has not been fully elucidated. We have found that NA (30 μM) exerts a bidirectional control on the magnitude of kainate-evoked (50-200 nM) gamma frequency oscillations in the cornu Ammonis (CA3) region of the rat hippocampus in vitro via activation of different receptor subtypes. Activation of alpha-adrenergic receptors (α-AR) reduced the power of the gamma frequency oscillation. In contrast, activation of beta-adrenergic receptors (β-AR) caused an increase in the power of the gamma frequency oscillations. Using specific agonists and antagonists of AR receptor subtypes we demonstrated that these effects are mediated specifically via α1A-AR and β1-AR subtypes. NA activated both receptor subtypes, but the α1A-AR-mediated effect predominated, resulting in a reversible suppression of gamma frequency activity. These results suggest that NA is able to differentially modulate on-going gamma frequency oscillatory activity that could result in either increased or decreased information flow through the hippocampus.

  11. Review of Studies Concerning Electromagnetic Field (EMF) Exposure Assessment in Europe: Low Frequency Fields (50 Hz–100 kHz)

    PubMed Central

    Gajšek, Peter; Ravazzani, Paolo; Grellier, James; Samaras, Theodoros; Bakos, József; Thuróczy, György

    2016-01-01

    We aimed to review the findings of exposure assessment studies done in European countries on the exposure of the general public to low frequency electric and magnetic fields (EMFs) of various frequencies. The study shows that outdoor average extremely low frequency magnetic fields (ELF-MF) in public areas in urban environments range between 0.05 and 0.2 µT in terms of flux densities, but stronger values (of the order of a few µT) may occur directly beneath high-voltage power lines, at the walls of transformer buildings, and at the boundary fences of substations. In the indoor environment, high values have been measured close to several domestic appliances (up to the mT range), some of which are held close to the body, e.g., hair dryers, electric shavers. Common sources of exposure to intermediate frequencies (IF) include induction cookers, compact fluorescent lamps, inductive charging systems for electric cars and security or anti-theft devices. No systematic measurement surveys or personal exposimetry data for the IF range have been carried out and only a few reports on measurements of EMFs around such devices are mentioned. According to the available European exposure assessment studies, three population exposure categories were classified by the authors regarding the possible future risk analysis. This classification should be considered a crucial advancement for exposure assessment, which is a mandatory step in any future health risk assessment of EMFs exposure. PMID:27598182

  12. A 99nW 70.4kHz Resistive Frequency Locking On-Chip Oscillator with 27.4ppm/°C Temperature Stability

    PubMed Central

    Choi, Myungjoon; Bang, Suyoung; Jang, Tae-Kwang; Blaauw, David; Sylvester, Dennis

    2015-01-01

    We present a low power on-chip oscillator for system-on-chip designs. The oscillator introduces a resistive frequency locking loop topology where the equivalent resistance of a switched-capacitor is matched to a temperature-compensated resistor. The approach eliminates the traditional comparator from the oscillation loop, which consumes significant power and limits temperature stability in conventional relaxation oscillators. The oscillator is fabricated in 0.18μm CMOS and exhibits 27.4ppm/°C and <7ppm long-term stability while consuming 99.4nW at 70.4 kHz. PMID:26855849

  13. Investigation of dielectric properties of polymer composites reinforced with carbon nanotubes in the frequency band of 0.01 Hz - 10 MHz

    NASA Astrophysics Data System (ADS)

    Goshev, A. A.; Eseev, M. K.; Kapustin, S. N.; Vinnik, L. N.; Volkov, A. S.

    2016-08-01

    The goal of this work is experimental study of dielectric properties of polymer nanocomposites reinforced with multiwalled carbon nanotubes (MWCNTs) in alternating electric field in low frequency band of 0.01 Hz - 10 MHz. We investigated the influence, functionalization degree, aspect ratio, concentration of carbon nanotubes (CNTs) on dielectric properties of polymer sample. We also studied the dependence of dielectric properties on the polymerization temperature. The dependence of CNTs agglomeration on sample polymerization temperature and temperature's influence on conductivity has been shown. We conducted model calculation of percolation threshold and figured out its dependence on CNTs aspect ratio.

  14. Modelling the spectral induced polarization response of water-saturated sands in the intermediate frequency range (102-105 Hz) using mechanistic and empirical approaches

    NASA Astrophysics Data System (ADS)

    Kremer, Thomas; Schmutz, Myriam; Leroy, Philippe; Agrinier, Pierre; Maineult, Alexis

    2016-11-01

    The intermediate frequency range 102-105 Hz forms the transition range between the spectral induced polarization frequency domain and the dielectric spectroscopy frequency domain. Available experimental data showed that the spectral induced polarization response of sands fully saturated with water was particularly sensitive to variations of the saturating water electrical conductivity value in the intermediate frequency range. An empirical and a mechanistic model have been developed and confronted to this experimental data. This confrontation showed that the Maxwell Wagner polarization alone is not sufficient to explain the observed signal in the intermediate frequency range. The SIP response of the media was modelled by assigning relatively high dielectric permittivity values to the sand particle or high effective permittivity values to the media. Such high values are commonly observed in the dielectric spectroscopy literature when entering the intermediate frequency range. The physical origin of these high dielectric permittivity values is discussed (grain shape, electromagnetic coupling), and a preliminary study is presented which suggests that the high impedance values of the non-polarizable electrodes might play a significant role in the observed behaviour.

  15. Effects of extremely low frequency electromagnetic field (50 Hz) on pentylenetetrazol-induced seizures in mice.

    PubMed

    Fadakar, Kaveh; Saba, Valiallah; Farzampour, Shahrokh

    2013-06-01

    The electromagnetic fields (EMF) have various behavioral and biological effects on human body. There are growing concerns about the consequences of exposure to EMF. However, some studies have shown beneficial effects of these waves on human. In this paper, we study the effect of acute, sub acute and long-term exposure to 50 Hz, 0.1 mT magnetic fields (MF) on the seizure induction threshold in mice. 64 mice are used and divided into four groups. Eight mice in any group were selected to be exposed to MF for specific duration and the others were used as a control group. The duration of the applied exposures was as follows: (1) 1 day (acute), (2) 3 days (sub acute), (3) 2 weeks (sub acute), (4) 1 month (long term). The mice were exposed 2 h for a day. After exposure, the pentylentetrazol (PTZ) is injected to the mice to induce seizure and the needed dose for the seizure induction threshold is measured. In the acute exposure, the threshold to induce seizure in the exposed and sham-exposed groups was 44.25 and 46.5 mg, respectively, while the difference was not significant (p value = 0.5). In the sub acute exposure (3 days), the mean amount of drug to induce seizure was 47.38 mg in the exposed and 43.88 mg in the sham-exposed groups, however, the difference was not significant (p value = 0.3). The results were 52.38 and 46.75 mg after 2 weeks of exposure which were not significantly different either (p value = 0.2). After 1 month of exposure to MF, the threshold for the induction of seizure was significantly increased (p value < 0.05). The mean dosage to induce seizure in the exposed and control group was 54.3 and 45.75 mg, respectively. However, considering the p value, the difference in the seizure induction threshold between the exposed and sham-exposed groups after acute and sub acute exposure was not significant, analyzing the effects of acute, sub acute and long-term exposures totally indicates that increasing the exposure time increases the

  16. Diverging frequency-modulated 50-kHz vocalization, locomotor activity and conditioned place preference effects in rats given repeated amphetamine treatment.

    PubMed

    Taracha, Ewa; Kaniuga, Ewelina; Chrapusta, Stanisław J; Maciejak, Piotr; Sliwa, Lech; Hamed, Adam; Krząścik, Paweł

    2014-08-01

    Behavioral sensitization and tolerance to repetitive exposure to addictive drugs are commonly used for the assessment of the early stages of the drug dependence progress in animals. The orchestra of tools for studying the progress of drug dependence in laboratory rodents has been considerably enriched in the 1980s by the introduction of ultrasonic vocalization (USV) detection and characterization. However, the relationship between the results of this technology and those of traditional behavioral tests is not clear. We attempted to elucidate some of the respective ambiguities by comparing the effects of an intermittent amphetamine treatment, which was aimed both at the induction of sensitization and tolerance to this drug and at testing the persistence of these effects, on the locomotor activity and 50-kHz USV responses to both the drug and the context of drug exposure in adult male rats showing diverging susceptibility for sensitization to amphetamine. Categorization of the rats into low and high responders/callers based on sensitization of their frequency-modulated 50-kHz USV responsiveness showed some correspondence with conditioned place preference effects, but not with responses to amphetamine. The study showed distinct changes in the rate and latency of the frequency-modulated 50-kHz USV responses to repetitive amphetamine treatment, which were reminiscent of classical behavioral signs of sensitization and tolerance. These results show the utility of the appetitive USV for monitoring of early phases of complex processes leading to drug dependence. However, USV, locomotor activity and conditioned place preference seem to reflect different aspects of these phenomena.

  17. Electric field of the power terrestrial sources observed by microsatellite Chibis-M in the Earth's ionosphere in frequency range 1-60 Hz

    NASA Astrophysics Data System (ADS)

    Dudkin, Fedir; Korepanov, Valery; Dudkin, Denis; Pilipenko, Vyacheslav; Pronenko, Vira; Klimov, Stanislav

    2015-07-01

    The power line emission (PLE) 50/60 Hz and the Schumann resonance (SR) harmonics were detected by the use of a compact electrical field sensor of length 0.42 m during microsatellite Chibis-M mission in years 2012-2014. The initial orbit of Chibis-M has altitude 500 km and inclination 52°. We present the space distribution of PLE and its connections with the possible overhead power lines. PLE has been recorded both in the shade and sunlit parts of the orbits as opposed to SR which have been recorded only in the nightside of the Earth. The cases of an extra long distance of PLE propagation in the Earth's ionosphere and increased value of SR Q factor have been also observed. These results should stimulate the ionosphere model refinement for ultralow frequency and extremely low frequency electromagnetic wave propagation as well as a study on new possibility of the ionosphere diagnostics.

  18. Comparative study of time-dependent effects of 4 and 8 Hz mechanical vibration at infrasound frequency on E. coli K-12 cells proliferation.

    PubMed

    Martirosyan, Varsik; Ayrapetyan, Sinerik

    2015-01-01

    The aim of the present work is to study the time-dependent effects of mechanical vibration (MV) at infrasound (IS) frequency at 4 and 8 Hz on E. coli K-12 growth by investigating the cell proliferation, using radioactive [(3)H]-thymidine assay. In our previous work it was suggested that the aqua medium can serve as a target through which the biological effect of MV on microbes could be realized. At the same time it was shown that microbes have mechanosensors on the surface of the cells and can sense small changes of the external environment. The obtained results were shown that the time-dependent effects of MV at 4 and 8 Hz frequency could either stimulate or inhibit the growth of microbes depending from exposure time. It more particularly, the invention relates to a method for controlling biological functions through the application of mechanical vibration, thus making it possible to artificially control the functions of bacterial cells, which will allow us to develop method that can be used in agriculture, industry, medicine, biotechnology to control microbial growth.

  19. Source model for strong ground motion generation in the frequency range 0.1-10 Hz during the 2011 Tohoku earthquake

    NASA Astrophysics Data System (ADS)

    Asano, Kimiyuki; Iwata, Tomotaka

    2012-12-01

    The source model of the 2011 Tohoku earthquake, which is composed of four strong motion generation areas (SMGAs), is estimated based on the broadband strong ground motion simulations in the frequency range 0.1-10 Hz using the empirical Green's function method. Two strong motion generation areas are identified in the Miyagi-oki region west of the hypocenter. Another two strong motion generation areas are located in the Fukushima-oki region southwest of the hypocenter. The strong ground motions in the frequency range 0.1-10 Hz along the Pacific coast are mainly controlled by these SMGAs. All the strong motion generation areas exist in the deeper portion of the source fault plane. The stress drops of the four SMGAs range from 6.6 to 27.8 MPa, which are similar to estimations for past M 7-class events occurring in this region. Compared with the slip models and aftershock distributions of past interplate earthquakes in the Miyagi-oki and Fukushima-oki regions since the 1930s, the SMGAs of the 2011 Tohoku earthquake spatially correspond to the asperities of M 7-class events in 1930s. In terms of broadband strong ground motions, the 2011 Tohoku earthquake is not only a tsunamigenic event with a huge coseismic slip near the trench but is also a complex event simultaneously rupturing pre-existing asperities.

  20. Comparative study of time-dependent effects of 4 and 8 Hz mechanical vibration at infrasound frequency on E. coli K-12 cells proliferation.

    PubMed

    Martirosyan, Varsik; Ayrapetyan, Sinerik

    2015-01-01

    The aim of the present work is to study the time-dependent effects of mechanical vibration (MV) at infrasound (IS) frequency at 4 and 8 Hz on E. coli K-12 growth by investigating the cell proliferation, using radioactive [(3)H]-thymidine assay. In our previous work it was suggested that the aqua medium can serve as a target through which the biological effect of MV on microbes could be realized. At the same time it was shown that microbes have mechanosensors on the surface of the cells and can sense small changes of the external environment. The obtained results were shown that the time-dependent effects of MV at 4 and 8 Hz frequency could either stimulate or inhibit the growth of microbes depending from exposure time. It more particularly, the invention relates to a method for controlling biological functions through the application of mechanical vibration, thus making it possible to artificially control the functions of bacterial cells, which will allow us to develop method that can be used in agriculture, industry, medicine, biotechnology to control microbial growth. PMID:24725172

  1. 10 kHz accuracy of an optical frequency reference based on (12)C2H2-filled large-core kagome photonic crystal fibers.

    PubMed

    Knabe, Kevin; Wu, Shun; Lim, Jinkang; Tillman, Karl A; Light, Philip S; Couny, Francois; Wheeler, Natalie; Thapa, Rajesh; Jones, Andrew M; Nicholson, Jeffrey W; Washburn, Brian R; Benabid, Fetah; Corwin, Kristan L

    2009-08-31

    Saturated absorption spectroscopy reveals the narrowest features so far in molecular gas-filled hollow-core photonic crystal fiber. The 48-68 mum core diameter of the kagome-structured fiber used here allows for 8 MHz full-width half-maximum sub-Doppler features, and its wavelength-insensitive transmission is suitable for high-accuracy frequency measurements. A fiber laser is locked to the (12)C2H2 nu(1); + nu(3) P(13) transition inside kagome fiber, and compared with frequency combs based on both a carbon nanotube fiber laser and a Cr:forsterite laser, each of which are referenced to a GPS-disciplined Rb oscillator. The absolute frequency of the measured line center agrees with those measured in power build-up cavities to within 9.3 kHz (1 sigma error), and the fractional frequency instability is less than 1.2 x 10(-11) at 1 s averaging time.

  2. Dielectric behavior of wild-type yeast and vacuole-deficient mutant over a frequency range of 10 kHz to 10 GHz.

    PubMed Central

    Asami, K; Yonezawa, T

    1996-01-01

    Dielectric behavior of Saccharomyces cerevisiae wild-type and vacuole-deficient mutant cells has been studied over a frequency range of 10 kHz to 10 GHz. Both types of cells harvested at the early stationary growth phase showed dielectric dispersion that was phenomenologically formulated by a sum of three separate dispersion terms: beta 1-dispersion (main dispersion) and beta 2-dispersion (additional dispersion) and gamma-dispersion due to orientation of water molecules. The beta 1-dispersion centered at a few MHz, which has been extensively studied so far, is due to interfacial polarization (or the Maxwell-Wagner effect) related to the plasma membrane. The beta 2-dispersion for the vacuole-deficient mutant centered at approximately 50 MHz was explained by taking the cell wall into account, whereas, for the wild-type cells, the beta 2-dispersion around a few tens MHz involved the contributions from the vacuole and cell wall. PMID:8889195

  3. Octave-wide frequency comb centered at 4 μm based on a subharmonic OPO with Hz-level relative comb linewidth

    NASA Astrophysics Data System (ADS)

    Smolski, V. O.; Xu, J.; Schunemann, P. G.; Vodopyanov, K. L.

    2016-03-01

    We study coherence properties of a more-than-octave-wide (2.6-7.5 μm) mid-IR frequency comb based on a 2-μm Tmfiber- laser-pumped degenerate (subharmonic) optical parametric oscillator (OPO) that uses orientation-patterned gallium arsenide (OP-GaAs) as gain element. By varying intracavity dispersion, we observed a 'phase' transition from a singlecomb state (at exactly OPO degeneracy) to a two-comb state (near-degenerate operation), characterized by two spectrally overlapping combs (signal and idler) with distinct carrier-envelope offset frequencies. We achieve this by generating a supercontinuum (SC) from the mode-locked Tm laser that spans most of the near-IR range, and observing RF beats between the SC and parasitic sum-frequency light (pump + OPO) that also falls into the near-IR. We found RF linewidth to be <15 Hz (a resolution of our spectrum analyzer), which proves that coherence of the pump laser comb is preserved to a high degree in a subharmonic OPO. Transition to a two-comb state was characterized by a symmetric splitting of the RF peak. Low pump threshold (down to 7 mW), high (73 mW) average power and high (up to 90%) pump depletion make this comb source very attractive for numerous applications including trace molecular detection and chemical sensing with massively parallel spectral data acquisition.

  4. Comparison of the genotoxic effects induced by 50 Hz extremely low-frequency electromagnetic fields and 1800 MHz radiofrequency electromagnetic fields in GC-2 cells.

    PubMed

    Duan, Weixia; Liu, Chuan; Zhang, Lei; He, Mindi; Xu, Shangcheng; Chen, Chunhai; Pi, Huifeng; Gao, Peng; Zhang, Yanwen; Zhong, Min; Yu, Zhengping; Zhou, Zhou

    2015-03-01

    Extremely low-frequency electromagnetic fields (ELF-EMF) and radiofrequency electromagnetic fields (RF-EMF) have been considered to be possibly carcinogenic to humans. However, their genotoxic effects remain controversial. To make experiments controllable and results comparable, we standardized exposure conditions and explored the potential genotoxicity of 50 Hz ELF-EMF and 1800 MHz RF-EMF. A mouse spermatocyte-derived GC-2 cell line was intermittently (5 min on and 10 min off) exposed to 50 Hz ELF-EMF at an intensity of 1, 2 or 3 mT or to RF-EMF in GSM-Talk mode at the specific absorption rates (SAR) of 1, 2 or 4 W/kg. After exposure for 24 h, we found that neither ELF-EMF nor RF-EMF affected cell viability using Cell Counting Kit-8. Through the use of an alkaline comet assay and immunofluorescence against γ-H2AX foci, we found that ELF-EMF exposure resulted in a significant increase of DNA strand breaks at 3 mT, whereas RF-EMF exposure had insufficient energy to induce such effects. Using a formamidopyrimidine DNA glycosylase (FPG)-modified alkaline comet assay, we observed that RF-EMF exposure significantly induced oxidative DNA base damage at a SAR value of 4 W/kg, whereas ELF-EMF exposure did not. Our results suggest that both ELF-EMF and RF-EMF under the same experimental conditions may produce genotoxicity at relative high intensities, but they create different patterns of DNA damage. Therefore, the potential mechanisms underlying the genotoxicity of different frequency electromagnetic fields may be different.

  5. Home Economics. Grades 10-12.

    ERIC Educational Resources Information Center

    Instructional Objectives Exchange, Los Angeles, CA.

    This collection contains 41 cognitive objectives and related test items for home economics, grades 10-12. It is organized into the following categories: child development (home discipline); clothing and textiles, consumer practices; design principals; health services, home management and family economics; housing; and pregnancy. Each objective is…

  6. Three Three-Year Aging of Prototype Flight Laser at 10 kHz and 1 ns Pulses With External Frequency Doubler for ICESat-2 Mission

    NASA Technical Reports Server (NTRS)

    Konoplev, Oleg A.; Chiragh, Furqan L.; Vasilyev, Aleksey A.; Edwards, Ryan; Stephen, Mark A.; Troupaki, Elisavet; Yu, Anthony W.; Krainak, Michael A.; Sawruk, Nick; Hovis, Floyd; Culpepper, Charles F.; Strickler, Kathy

    2016-01-01

    We present the results of three year life-aging of a specially designed prototype flight source laser operating at 1064 nm, 10 kHz, 1ns, 15W average power and external frequency doubler. The Fibertek-designed, slightly pressurized air, enclosed-container source laser operated at 1064 nm in active Q-switching mode. The external frequency doubler was set in a clean room at a normal air pressure. The goal of the experiment was to measure degradation modes at 1064 and 532 nm discreetly. The external frequency doubler consisted of a Lithium triborate, LiB3O5, crystal operated at non-critical phase-matching. Due to 1064 nm diagnostic needs, the amount of fundamental frequency power available for doubling was 13.7W. The power generated at 532 nm was between 8.5W and 10W, depending on the level of stress and degradation. The life-aging consisted of double stress-step operation for doubler crystal, at 0.35 Jcm2 for almost 1 year, corresponding to normal conditions, and then at 0.93 Jcm2 for the rest of the experiment, corresponding to accelerated testing. We observed no degradation at the first step and linear degradation at the second step. The linear degradation at the second stress-step was related to doubler crystal output surface changes and linked to laser-assisted contamination. We discuss degradation model and estimate the expected lifetime for the flight laser at 532 nm. This work was done within the laser testing for NASAs Ice, Cloud, and land Elevation Satellite-2 (ICESat-2) LIDAR at Goddard Space Flight Center in Greenbelt, MD with the goal of 1 trillion shots lifetime.

  7. In Vitro Developmental Neurotoxicity Following Chronic Exposure to 50 Hz Extremely Low-Frequency Electromagnetic Fields in Primary Rat Cortical Cultures.

    PubMed

    de Groot, Martje W G D M; van Kleef, Regina G D M; de Groot, Aart; Westerink, Remco H S

    2016-02-01

    Exposure to 50-60 Hz extremely low-frequency electromagnetic fields (ELF-EMFs) has increased considerably over the last decades. Several epidemiological studies suggested that ELF-EMF exposure is associated with adverse health effects, including neurotoxicity. However, these studies are debated as results are often contradictory and the possible underlying mechanisms are unknown. Since the developing nervous system is particularly vulnerable to insults, we investigate effects of chronic, developmental ELF-EMF exposure in vitro. Primary rat cortical neurons received 7 days developmental exposure to 50 Hz block-pulsed ELF-EMF (0-1000 μT) to assess effects on cell viability (Alamar Blue/CFDA assay), calcium homeostasis (single cell fluorescence microscopy), neurite outgrowth (β(III)-Tubulin immunofluorescent staining), and spontaneous neuronal activity (multi-electrode arrays). Our data demonstrate that cell viability is not affected by developmental ELF-EMF (0-1000 μT) exposure. Depolarization- and glutamate-evoked increases in intracellular calcium concentration ([Ca(2+)]i) are slightly increased at 1 μT, whereas both basal and stimulation-evoked [Ca(2+)]i show a modest inhibition at 1000 μT. Subsequent morphological analysis indicated that neurite length is unaffected up to 100 μT, but increased at 1000 μT. However, neuronal activity appeared largely unaltered following chronic ELF-EMF exposure up to 1000 μT. The effects of ELF-EMF exposure were small and largely restricted to the highest field strength (1000 μT), ie, 10 000 times above background exposure and well above current residential exposure limits. Our combined data therefore indicate that chronic ELF-EMF exposure has only limited (developmental) neurotoxic potential in vitro.

  8. Extremely low frequency magnetic field (50 Hz, 0.5 mT) reduces oxidative stress in the brain of gerbils submitted to global cerebral ischemia.

    PubMed

    Rauš Balind, Snežana; Selaković, Vesna; Radenović, Lidija; Prolić, Zlatko; Janać, Branka

    2014-01-01

    Magnetic field as ecological factor has influence on all living beings. The aim of this study was to determine if extremely low frequency magnetic field (ELF-MF, 50 Hz, 0.5 mT) affects oxidative stress in the brain of gerbils submitted to 10-min global cerebral ischemia. After occlusion of both carotid arteries, 3-month-old gerbils were continuously exposed to ELF-MF for 7 days. Nitric oxide and superoxide anion production, superoxide dismutase activity and index of lipid peroxidation were examined in the forebrain cortex, striatum and hippocampus on the 7(th) (immediate effect of ELF-MF) and 14(th) day after reperfusion (delayed effect of ELF-MF). Ischemia per se increased oxidative stress in the brain on the 7(th) and 14(th) day after reperfusion. ELF-MF also increased oxidative stress, but to a greater extent than ischemia, only immediately after cessation of exposure. Ischemic gerbils exposed to ELF-MF had increased oxidative stress parameters on the 7(th) day after reperfusion, but to a lesser extent than ischemic or ELF-MF-exposed animals. On the 14(th) day after reperfusion, oxidative stress parameters in the brain of these gerbils were mostly at the control levels. Applied ELF-MF decreases oxidative stress induced by global cerebral ischemia and thereby reduces possible negative consequences which free radical species could have in the brain. The results presented here indicate a beneficial effect of ELF-MF (50 Hz, 0.5 mT) in the model of global cerebral ischemia.

  9. Extremely Low Frequency Magnetic Field (50 Hz, 0.5 mT) Reduces Oxidative Stress in the Brain of Gerbils Submitted to Global Cerebral Ischemia

    PubMed Central

    Rauš Balind, Snežana; Selaković, Vesna; Radenović, Lidija; Prolić, Zlatko; Janać, Branka

    2014-01-01

    Magnetic field as ecological factor has influence on all living beings. The aim of this study was to determine if extremely low frequency magnetic field (ELF-MF, 50 Hz, 0.5 mT) affects oxidative stress in the brain of gerbils submitted to 10-min global cerebral ischemia. After occlusion of both carotid arteries, 3-month-old gerbils were continuously exposed to ELF-MF for 7 days. Nitric oxide and superoxide anion production, superoxide dismutase activity and index of lipid peroxidation were examined in the forebrain cortex, striatum and hippocampus on the 7th (immediate effect of ELF-MF) and 14th day after reperfusion (delayed effect of ELF-MF). Ischemia per se increased oxidative stress in the brain on the 7th and 14th day after reperfusion. ELF-MF also increased oxidative stress, but to a greater extent than ischemia, only immediately after cessation of exposure. Ischemic gerbils exposed to ELF-MF had increased oxidative stress parameters on the 7th day after reperfusion, but to a lesser extent than ischemic or ELF-MF-exposed animals. On the 14th day after reperfusion, oxidative stress parameters in the brain of these gerbils were mostly at the control levels. Applied ELF-MF decreases oxidative stress induced by global cerebral ischemia and thereby reduces possible negative consequences which free radical species could have in the brain. The results presented here indicate a beneficial effect of ELF-MF (50 Hz, 0.5 mT) in the model of global cerebral ischemia. PMID:24586442

  10. Effects of long-term 50Hz power-line frequency electromagnetic field on cell behavior in Balb/c 3T3 cells.

    PubMed

    An, Guang-Zhou; Xu, Hui; Zhou, Yan; Du, Le; Miao, Xia; Jiang, Da-Peng; Li, Kang-Chu; Guo, Guo-Zhen; Zhang, Chen; Ding, Gui-Rong

    2015-01-01

    Power-line frequency electromagnetic field (PF-EMF) was reported as a human carcinogen by some epidemiological research, but the conclusion is lack of robust experiment evidence. To identify the effects of long-term PF-EMF exposure on cell behavior, Balb/c 3T3 cells in exponential growth phase were exposed or sham-exposed to 50 Hertz (Hz) PF-EMF at 2.3 mT for 2 hours (h) one day, 5 days every week. After 11 weeks exposure, cells were collected instantly. Cell morphology was observed under invert microscope and Giemsa staining, cell viability was detected by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay, cell cycle and apoptosis was examined by flow cytometry, the protein level of Proliferating Cell Nuclear Antigen (PCNA) and CyclinD1 was detected by western blot, cell transformation was examined by soft agar clone assay and plate clone forming test, and cell migration ability was observed by scratch adhesion test. It was found that after PF-EMF exposure, cell morphology, apoptosis, cell migration ability and cell transformation didn't change. However, compared with sham group, cell viability obviously decreased and cell cycle distribution also changed after 11 weeks PF-EMF exposure. Meanwhile, the protein level of PCNA and CyclinD1 significantly decreased after PF-EMF exposure. These data suggested that although long-term 50Hz PF-EMF exposure under this experimental condition had no effects on apoptosis, cell migration ability and cell transformation, it could affect cell proliferation and cell cycle by down-regulation the expression of PCNA and CyclinD1 protein.

  11. Three-year aging of prototype flight laser at 10 kHz and 1 ns pulses with external frequency doubler for ICESat-2 mission

    NASA Astrophysics Data System (ADS)

    Konoplev, Oleg A.; Chiragh, Furqan L.; Vasilyev, Aleksey A.; Edwards, Ryan; Stephen, Mark A.; Troupaki, Elisavet; Yu, Anthony W.; Krainak, Michael A.; Sawruk, Nick; Hovis, Floyd; Culpepper, Charles F.; Strickler, Kathy

    2016-05-01

    We present the results of a three-year operational-aging test of a specially designed prototype flight laser operating at 1064 nm, 10 kHz, 1ns, 15W average power and externally frequency-doubled. Fibertek designed and built the q-switched, 1064nm laser and this laser was in a sealed container of dry air pressurized to 1.3 atm. The external frequency doubler was in a clean room at a normal air pressure. The goal of the experiment was to measure degradation modes at 1064 and 532 nm separately. The external frequency doubler consisted of a Lithium triborate, LiB3O5, non-critically phase-matched crystal. After some 1064 nm light was diverted for diagnostics, 13.7W of fundamental power was available to pump the doubling crystal. Between 8.5W and 10W of 532nm power was generated, depending on the level of stress and degradation. The test consisted of two stages, the first at 0.3 J/cm2 for almost 1 year, corresponding to expected operational conditions, and the second at 0.93 J/cm2 for the remainder of the experiment, corresponding to accelerated optical stress testing. We observed no degradation at the first stress-level and linear degradation at the second stress-level. The linear degradation was linked to doubler crystal output surface changes from laser-assisted contamination. We estimate the expected lifetime for the flight laser at 532 nm using fluence as the stress parameter. This work was done for NASA's Ice, Cloud, and land Elevation Satellite-2 (ICESat-2) LIDAR at Goddard Space Flight Center in Greenbelt, MD with the goal of 1 trillion shots lifetime.

  12. The effect of extremely low-frequency magnetic field (50–60 Hz) exposure on spontaneous apoptosis: The results of a meta-analysis

    PubMed Central

    Mansourian, Mahsa; Marateb, Hamid Reza; Vaseghi, Golnaz

    2016-01-01

    Background: This paper is a meta-analysis of the published data from in vitro studies to evaluate whether spontaneous apoptosis might be influenced by extremely low frequency (ELF) magnetic fields (MFs). Materials and Methods: A comprehensive scientific literature search in electronic databases was conducted and studies covering the period 2000–2010 were selected. Then, published studies involving the desired topic were retrieved. The inclusion criteria were percentage of apoptosis in the cells exposed to 50–60 Hz ELF-MFs. The statistical analysis was performed by comprehensive meta-analysis version 2. Results: The summary measure of association (95% confidence interval) for all 18 effect estimated from 8 studies was 1.18 (1.15, 1.20). Heterogeneity among studies was found. There was no evidence of publication bias for the association between exposure to MF and apoptosis risk. Conclusion: Our meta-analysis provided conclusive data that ELF-MFs can increase apoptosis in cancer and normal cells. Furthermore, there is a possibly individual intensity and time range with maximum created effect according to window effect. PMID:27656610

  13. Neuritin reverses deficits in murine novel object associative recognition memory caused by exposure to extremely low-frequency (50 Hz) electromagnetic fields

    PubMed Central

    Zhao, Qian-Ru; Lu, Jun-Mei; Yao, Jin-Jing; Zhang, Zheng-Yu; Ling, Chen; Mei, Yan-Ai

    2015-01-01

    Animal studies have shown that electromagnetic field exposure may interfere with the activity of brain cells, thereby generating behavioral and cognitive disturbances. However, the underlying mechanisms and possible preventions are still unknown. In this study, we used a mouse model to examine the effects of exposure to extremely low-frequency (50 Hz) electromagnetic fields (ELF MFs) on a recognition memory task and morphological changes of hippocampal neurons. The data showed that ELF MFs exposure (1 mT, 12 h/day) induced a time-dependent deficit in novel object associative recognition memory and also decreased hippocampal dendritic spine density. This effect was observed without corresponding changes in spontaneous locomotor activity and was transient, which has only been seen after exposing mice to ELF MFs for 7-10 days. The over-expression of hippocampal neuritin, an activity-dependent neurotrophic factor, using an adeno-associated virus (AAV) vector significantly increased the neuritin level and dendritic spine density. This increase was paralleled with ELF MFs exposure-induced deficits in recognition memory and reductions of dendritic spine density. Collectively, our study provides evidence for the association between ELF MFs exposure, impairment of recognition memory, and resulting changes in hippocampal dendritic spine density. Neuritin prevented this ELF MFs-exposure-induced effect by increasing the hippocampal spine density. PMID:26138388

  14. Neuritin reverses deficits in murine novel object associative recognition memory caused by exposure to extremely low-frequency (50 Hz) electromagnetic fields.

    PubMed

    Zhao, Qian-Ru; Lu, Jun-Mei; Yao, Jin-Jing; Zhang, Zheng-Yu; Ling, Chen; Mei, Yan-Ai

    2015-01-01

    Animal studies have shown that electromagnetic field exposure may interfere with the activity of brain cells, thereby generating behavioral and cognitive disturbances. However, the underlying mechanisms and possible preventions are still unknown. In this study, we used a mouse model to examine the effects of exposure to extremely low-frequency (50 Hz) electromagnetic fields (ELF MFs) on a recognition memory task and morphological changes of hippocampal neurons. The data showed that ELF MFs exposure (1 mT, 12 h/day) induced a time-dependent deficit in novel object associative recognition memory and also decreased hippocampal dendritic spine density. This effect was observed without corresponding changes in spontaneous locomotor activity and was transient, which has only been seen after exposing mice to ELF MFs for 7-10 days. The over-expression of hippocampal neuritin, an activity-dependent neurotrophic factor, using an adeno-associated virus (AAV) vector significantly increased the neuritin level and dendritic spine density. This increase was paralleled with ELF MFs exposure-induced deficits in recognition memory and reductions of dendritic spine density. Collectively, our study provides evidence for the association between ELF MFs exposure, impairment of recognition memory, and resulting changes in hippocampal dendritic spine density. Neuritin prevented this ELF MFs-exposure-induced effect by increasing the hippocampal spine density. PMID:26138388

  15. The effect of extremely low-frequency magnetic field (50–60 Hz) exposure on spontaneous apoptosis: The results of a meta-analysis

    PubMed Central

    Mansourian, Mahsa; Marateb, Hamid Reza; Vaseghi, Golnaz

    2016-01-01

    Background: This paper is a meta-analysis of the published data from in vitro studies to evaluate whether spontaneous apoptosis might be influenced by extremely low frequency (ELF) magnetic fields (MFs). Materials and Methods: A comprehensive scientific literature search in electronic databases was conducted and studies covering the period 2000–2010 were selected. Then, published studies involving the desired topic were retrieved. The inclusion criteria were percentage of apoptosis in the cells exposed to 50–60 Hz ELF-MFs. The statistical analysis was performed by comprehensive meta-analysis version 2. Results: The summary measure of association (95% confidence interval) for all 18 effect estimated from 8 studies was 1.18 (1.15, 1.20). Heterogeneity among studies was found. There was no evidence of publication bias for the association between exposure to MF and apoptosis risk. Conclusion: Our meta-analysis provided conclusive data that ELF-MFs can increase apoptosis in cancer and normal cells. Furthermore, there is a possibly individual intensity and time range with maximum created effect according to window effect.

  16. Laboratory investigation of the acoustic response of seagrass tissue in the frequency band 0.5-2.5 kHz.

    PubMed

    Wilson, Preston S; Dunton, Kenneth H

    2009-04-01

    Previous in situ investigations of seagrass have revealed acoustic phenomena that depend on plant density, tissue gas content, and free bubbles produced by photosynthetic activity, but corresponding predictive models that could be used to optimize acoustic remote sensing, shallow water sonar, and mine hunting applications have not appeared. To begin to address this deficiency, low frequency (0.5-2.5 kHz) acoustic laboratory experiments were conducted on three freshly collected Texas Gulf Coast seagrass species. A one-dimensional acoustic resonator technique was used to assess the biomass and effective acoustic properties of the leaves and rhizomes of Thalassia testudinum (turtle grass), Syringodium filiforme (manatee grass), and Halodule wrightii (shoal grass). Independent biomass and gas content estimates were obtained via microscopic cross-section imagery. The acoustic results were compared to model predictions based on Wood's equation for a two-phase medium. The effective sound speed in the plant-filled resonator was strongly dependent on plant biomass, but the Wood's equation model (based on tissue gas content alone) could not predict the effective sound speed for the low irradiance conditions of the experiment, in which no free bubbles were generated by photosynthesis. The results corroborate previously published results obtained in situ for another seagrass species, Posidonia oceanica. PMID:19354371

  17. Laboratory investigation of the acoustic response of seagrass tissue in the frequency band 0.5-2.5 kHz.

    PubMed

    Wilson, Preston S; Dunton, Kenneth H

    2009-04-01

    Previous in situ investigations of seagrass have revealed acoustic phenomena that depend on plant density, tissue gas content, and free bubbles produced by photosynthetic activity, but corresponding predictive models that could be used to optimize acoustic remote sensing, shallow water sonar, and mine hunting applications have not appeared. To begin to address this deficiency, low frequency (0.5-2.5 kHz) acoustic laboratory experiments were conducted on three freshly collected Texas Gulf Coast seagrass species. A one-dimensional acoustic resonator technique was used to assess the biomass and effective acoustic properties of the leaves and rhizomes of Thalassia testudinum (turtle grass), Syringodium filiforme (manatee grass), and Halodule wrightii (shoal grass). Independent biomass and gas content estimates were obtained via microscopic cross-section imagery. The acoustic results were compared to model predictions based on Wood's equation for a two-phase medium. The effective sound speed in the plant-filled resonator was strongly dependent on plant biomass, but the Wood's equation model (based on tissue gas content alone) could not predict the effective sound speed for the low irradiance conditions of the experiment, in which no free bubbles were generated by photosynthesis. The results corroborate previously published results obtained in situ for another seagrass species, Posidonia oceanica.

  18. [Proton generator of superhigh frequency].

    PubMed

    Liberman, E A; Eĭdus, V L

    1981-01-01

    Possible mechanism of superhigh frequency (10(10)-10(12) Hz) electromagnetic oscillation generation by an external proton in a system of hydrogen bonds of biomacromolecules is briefly discussed. The external proton in a proton channel deforms the potential profile of the proton of hydrogen bond in such a way, that there appears a possibility of the low frequency proton tunneling along the hydrogen bond. The interaction with the neighbouring bonds leads to further lowering of the generated frequency.

  19. 47 CFR 80.374 - Provisions for frequencies in the 4000-4063 and the 8100-8195 kHz bands shared with the fixed...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... the 8100-8195 kHz bands shared with the fixed service. 80.374 Section 80.374 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES STATIONS IN THE MARITIME SERVICES... shared with the fixed service. Coast station assignments in the 4000-4063 kHz band deviate...

  20. [Polish regulations on maximum admissible intensities for electric and magnetic frequencies of 60 Hz and the European Union recommendations for electrical power engineering].

    PubMed

    Groszko, Marian

    2003-01-01

    Electric and magnetic fields of 50 Hz from electric power devices affect not only workers, but also the general population, as these devices are also located in populated areas, hence the duality of regulations on maximum admissible intensities. This paper presents these regulations and discusses in detail the changes of 2001. Based on the Polish regulations, hygienic evaluation of electric power devices has been attempted. The Polish regulations on the 50 Hz electromagnetic fields were compared with relevant international regulations of CENELEC and the European Union recommendations. Our maximum admissible intensities have been found to conform with the international standards.

  1. Search for a correlation between kHz quasi-periodic oscillation frequencies and accretion-related parameters in the ensemble of neutron star low-mass X-ray binaries

    NASA Astrophysics Data System (ADS)

    Çatmabacak, Önder; Erkut, M. Hakan; Catmabacak, Onur; Duran, Sivan

    2016-07-01

    The distribution of neutron star sources in the ensemble of low-mass X-ray binaries shows no evidence for a correlation between kHz quasi-periodic oscillation (QPO) frequencies and X-ray luminosity. Sources differing by orders of magnitude in luminosity can exhibit similar range of QPO frequencies. We study the possibility for the existence of a correlation between kHz QPO frequencies and accretion related parameters. The parameters such as the mass accretion rate and the size of the boundary region in the innermost disk are expected to be related to X-ray luminosity. Using the up-to-date data of neutron star low-mass X-ray binaries, we search for a possible correlation between lower kHz QPO frequencies and mass accretion rate through the mass and radius values predicted by different equations of state for the neutron star. The range of mass accretion rate for each source can be estimated if the accretion luminosity is assumed to be represented well by the X-ray luminosity of the source. Although we find no correlation between mass accretion rate and QPO frequencies, the source distribution seems to be in accordance with a correlation between kHz QPO frequencies and the parameter combining the neutron star magnetic field and the mas accretion rate. The model function we employ to descibe the correlation is able to account for the scattering of individual sources around a simple power law. The correlation argues disk-magnetosphere interaction as the origin of these millisecond oscillations.

  2. The effects of water content and water resistivity on the dispersion of resistivity and dielectric constant in quartz sand in the frequency range 10^2 to 10^8 Hz

    USGS Publications Warehouse

    Eberle, W.R.

    1983-01-01

    Using modifications of previously developed methods, measurements were made of the resistivity and the dielectric constant of two similar quartz sands of different porosity over the frequency range 102-108 Hertz for various water contents and water resistivities. Dispersion is pronounced in all the resistivity data above 106 Hz. As water content decreases, resistivity dispersion becomes noticeable at lower frequencies. The resistivity data at all frequencies, however, fit an empirical prediction formula relating observed resistivity to water saturation and resistivity of the saturated sample. The data suggest that the dispersion of resistivity of some earth materials with frequency may be predicted on the basis of curve matching of the data obtained in this investigation with the resistivity of the material at a frequency of 100 Hz or lower. The dispersion of dielectric constant with frequency is pronounced at all frequencies, being more pronounced with increasing water content. The shape of the dispersion curve is dependent on the resistivity of the water in the sample.

  3. A Toy Model for 3:2 Ratio of kHz QPO Frequency in Black Hole X-ray Binaries

    NASA Astrophysics Data System (ADS)

    Wang, Ding-Xiong; Ye, Yong-Chun; Ma, Ren-Yi; Gong, Xiao-Long

    2005-06-01

    Production of pairs of high frequency quasi-periodic oscillations (QPOs) in black hole X-ray binaries is discussed based on a model of non-axisymmetric magnetic coupling of a rotating black hole (BH) with its surrounding accretion disk, in which a puzzling 3:2 ratio of the upper frequency to the lower frequency is explained. In addition, the correlation of the pairs of high frequency QPOs with the jets from microquasars is discussed.

  4. 24 CFR 10.12 - Additional rulemaking proceedings.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 24 Housing and Urban Development 1 2010-04-01 2010-04-01 false Additional rulemaking proceedings. 10.12 Section 10.12 Housing and Urban Development Office of the Secretary, Department of Housing and Urban Development RULEMAKING: POLICY AND PROCEDURES Procedures § 10.12 Additional rulemaking proceedings. The Secretary may invite interested...

  5. 46 CFR 90.10-12 - Gas free.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 4 2011-10-01 2011-10-01 false Gas free. 90.10-12 Section 90.10-12 Shipping COAST GUARD... Terms Used in This Subchapter § 90.10-12 Gas free. This term means free from dangerous concentrations of flammable or toxic gases....

  6. 46 CFR 90.10-12 - Gas free.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Gas free. 90.10-12 Section 90.10-12 Shipping COAST GUARD... Terms Used in This Subchapter § 90.10-12 Gas free. This term means free from dangerous concentrations of flammable or toxic gases....

  7. 46 CFR 90.10-12 - Gas free.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 4 2013-10-01 2013-10-01 false Gas free. 90.10-12 Section 90.10-12 Shipping COAST GUARD... Terms Used in This Subchapter § 90.10-12 Gas free. This term means free from dangerous concentrations of flammable or toxic gases....

  8. 46 CFR 90.10-12 - Gas free.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 4 2012-10-01 2012-10-01 false Gas free. 90.10-12 Section 90.10-12 Shipping COAST GUARD... Terms Used in This Subchapter § 90.10-12 Gas free. This term means free from dangerous concentrations of flammable or toxic gases....

  9. 46 CFR 90.10-12 - Gas free.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 4 2014-10-01 2014-10-01 false Gas free. 90.10-12 Section 90.10-12 Shipping COAST GUARD... Terms Used in This Subchapter § 90.10-12 Gas free. This term means free from dangerous concentrations of flammable or toxic gases....

  10. 1 CFR 10.12 - Format, indexes, and ancillaries.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 1 General Provisions 1 2014-01-01 2012-01-01 true Format, indexes, and ancillaries. 10.12 Section 10.12 General Provisions ADMINISTRATIVE COMMITTEE OF THE FEDERAL REGISTER SPECIAL EDITIONS OF THE FEDERAL REGISTER PRESIDENTIAL PAPERS Annual Publication § 10.12 Format, indexes, and ancillaries. (a)...

  11. 1 CFR 10.12 - Format, indexes, and ancillaries.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 1 General Provisions 1 2012-01-01 2012-01-01 false Format, indexes, and ancillaries. 10.12 Section 10.12 General Provisions ADMINISTRATIVE COMMITTEE OF THE FEDERAL REGISTER SPECIAL EDITIONS OF THE FEDERAL REGISTER PRESIDENTIAL PAPERS Annual Publication § 10.12 Format, indexes, and ancillaries. (a)...

  12. 1 CFR 10.12 - Format, indexes, and ancillaries.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 1 General Provisions 1 2013-01-01 2012-01-01 true Format, indexes, and ancillaries. 10.12 Section 10.12 General Provisions ADMINISTRATIVE COMMITTEE OF THE FEDERAL REGISTER SPECIAL EDITIONS OF THE FEDERAL REGISTER PRESIDENTIAL PAPERS Annual Publication § 10.12 Format, indexes, and ancillaries. (a)...

  13. 1 CFR 10.12 - Format, indexes, and ancillaries.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 1 General Provisions 1 2010-01-01 2010-01-01 false Format, indexes, and ancillaries. 10.12 Section 10.12 General Provisions ADMINISTRATIVE COMMITTEE OF THE FEDERAL REGISTER SPECIAL EDITIONS OF THE FEDERAL REGISTER PRESIDENTIAL PAPERS Annual Publication § 10.12 Format, indexes, and ancillaries. (a)...

  14. 1 CFR 10.12 - Format, indexes, and ancillaries.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 1 General Provisions 1 2011-01-01 2011-01-01 false Format, indexes, and ancillaries. 10.12 Section 10.12 General Provisions ADMINISTRATIVE COMMITTEE OF THE FEDERAL REGISTER SPECIAL EDITIONS OF THE FEDERAL REGISTER PRESIDENTIAL PAPERS Annual Publication § 10.12 Format, indexes, and ancillaries. (a)...

  15. Audiogram of the chicken (Gallus gallus domesticus) from 2 Hz to 9 kHz.

    PubMed

    Hill, Evan M; Koay, Gimseong; Heffner, Rickye S; Heffner, Henry E

    2014-10-01

    The pure-tone thresholds of four domestic female chickens were determined from 2 Hz to 9 kHz using the method of conditioned suppression/avoidance. At a level of 60 dB sound pressure level (re 20 μN/m(2)), their hearing range extends from 9.1 Hz to 7.2 kHz, with a best sensitivity of 2.6 dB at 2 kHz. Chickens have better sensitivity than humans for frequencies below 64 Hz; indeed, their sensitivity to infrasound exceeds that of the homing pigeon. However, when threshold testing moved to the lower frequencies, the animals required additional training before their final thresholds were obtained, suggesting that they may perceive frequencies below 64 Hz differently than higher frequencies. PMID:25092127

  16. Dual frequency nematic liquid crystal spatial light modulator with modulation depth 0-2pi and operation rate in hundreds Hz region

    NASA Astrophysics Data System (ADS)

    Beresnev, Leonid A.; Carhart, Gary W.; Campbell, David; Gonglewski, John D.; Dayton, David C.

    2002-09-01

    The experimental search of the shape of electrical voltage is presented for controlling the optical phase modulator based on dual frequency nematic liquid crystal. Two basic approaches were tested. One is based on universal relation between two driving frequencies, below and above inversion point, respectively. Another approach uses the combination of pulses of both frequencies, which allow us, at first, to provide the fast transition between chosen retardations and , at second, to hold final retardation for the necessary duration.

  17. Rats showing low and high sensitization of frequency-modulated 50-kHz vocalization response to amphetamine differ in amphetamine-induced brain Fos expression.

    PubMed

    Kaniuga, Ewelina; Taracha, Ewa; Stępień, Tomasz; Wierzba-Bobrowicz, Teresa; Płaźnik, Adam; Chrapusta, Stanisław J

    2016-10-01

    Individuals predisposed to addiction constitute a minority of drug users, in both humans and animal models of the disorder, but there are no established characteristics that would allow identifying them beforehand. Our studies demonstrate that sensitization of rat 50-kHz ultrasonic vocalization (USV) response to amphetamine shows marked inter-individual diversity but substantial intra-individual stability. Low sensitization of the response shows relevance to the acquisition of self-administration of this drug and hence might be of predictive value regarding the risk of addiction. We compared amphetamine-induced Fos expression in 16 brain regions considered important for the development of addiction between rats preselected for low and high sensitization of the response and next given nine daily amphetamine doses followed by a 2-week withdrawal and final amphetamine challenge. Ventral tegmental area and nucleus accumbens shell Fos-positive nuclei counts correlated positively with 50-kHz USV response to the challenge in high-sensitized rats. Compared to those in amphetamine-untreated controls, Fos-positive nuclei counts were significantly and markedly (2-6 times) higher in 12 regions in high-sensitized rats, whereas in low-sensitized rats they were significantly higher in the cingulate cortex and dorsomedial striatum only. The difference in the counts between the latter two subsets reached statistical significance in dorsomedial and dorsolateral striatum and three out of four cortical regions studied. The fact that the diversification was most distinct in dorsal striatum that plays a critical role in the transition from controlled to compulsive drug intake suggests that the USV-based categorization may be related to divergent vulnerability of rats to AMPH addiction. PMID:27507424

  18. Compact stabilized semiconductor laser for frequency metrology.

    PubMed

    Liang, Wei; Ilchenko, Vladimir S; Eliyahu, Danny; Dale, Elijah; Savchenkov, Anatoliy A; Seidel, David; Matsko, Andrey B; Maleki, Lute

    2015-04-10

    We report on the development of a frequency modulatable 795 nm semiconductor laser based on self-injection locking to a high-quality-factor whispering-gallery-mode microresonator. The laser is characterized by residual amplitude modulation below -80  dB and frequency noise better than 300  Hz/Hz(1/2) at offset frequencies ranging from 100 Hz to 10 MHz. The frequency modulation speed and span of the laser exceed 1 MHz and 4 GHz, respectively. Locking of the laser to the Doppler-free saturated absorption resonance of the (87)Rb D1 line is demonstrated and relative frequency stability better than 10(-12) is measured for integration time spanning from 1 s to 1 day. The architecture demonstrated in this study is suitable for the realization of frequency modulatable lasers at any wavelength.

  19. Comparison of 10-kHz High-Frequency and Traditional Low-Frequency Spinal Cord Stimulation for the Treatment of Chronic Back and Leg Pain: 24-Month Results From a Multicenter, Randomized, Controlled Pivotal Trial

    PubMed Central

    Yu, Cong; Doust, Matthew W.; Gliner, Bradford E.; Vallejo, Ricardo; Sitzman, B. Todd; Amirdelfan, Kasra; Morgan, Donna M.; Yearwood, Thomas L.; Bundschu, Richard; Yang, Thomas; Benyamin, Ramsin; Burgher, Abram H.

    2016-01-01

    BACKGROUND: Pain relief with spinal cord stimulation (SCS) has focused historically on paresthesias overlapping chronically painful areas. A higher level evidence supports the use of SCS in treating leg pain than supports back pain, as it is difficult to achieve adequate paresthesia coverage, and then pain relief, in the low back region. In comparison, 10-kHz high-frequency (HF10 therapy) SCS therapy does not rely on intraoperative paresthesia mapping and remains paresthesia-free during therapy. OBJECTIVE: To compare long-term results of HF10 therapy and traditional low-frequency SCS. METHODS: A pragmatic randomized, controlled, pivotal trial with 24-month follow-up was conducted across 11 comprehensive pain treatment centers. Subjects had Visual Analog Scale scores of ≥5.0/10.0 cm for both back and leg pain, and were assigned randomly (1:1) to receive HF10 therapy or low-frequency SCS. The primary end point was a responder rate, defined as ≥50% back pain reduction from baseline at 3 months with a secondary end point at 12 months (previously reported). In this article, 24-month secondary results are presented. Non-inferiority was first assessed, and if demonstrated the results were tested for superiority. RESULTS: In the study, 198 subjects were randomized (101 HF10 therapy, 97 traditional SCS). One hundred seventy-one subjects (90 HF10 therapy, 81 traditional SCS) successfully completed a short-term trial and were implanted. Subjects averaged 54.9 ± 12.9 years old, 13.6 ± 11.3 years since diagnosis, 86.6% had back surgery, 88.3% were taking opioid analgesics. At 3 months, 84.5% of implanted HF10 therapy subjects were responders for back pain and 83.1% for leg pain, and 43.8% of traditional SCS subjects were responders for back pain and 55.5% for leg pain (P < .001 for both back and leg pain comparisons, non-inferiority and superiority). At 24 months, more subjects were responders to HF10 therapy than traditional SCS (back pain: 76.5% vs 49.3%; 27

  20. Behavior of 1 Ω resistors at frequencies below 1 Hz and the problem of assigning a dc value

    NASA Astrophysics Data System (ADS)

    Fletcher, Nick; Götz, Martin; Rolland, Benjamin; Pesel, Eckart

    2015-08-01

    This paper presents a systematic study of the effects of reversals of current polarity on 1 Ω standard resistors. A selection of 1 Ω standards were measured on a dc cryogenic current comparator bridge and also on an ac current comparator bridge operating at 1 Hz. We find that the apparent 4 terminal resistance depends strongly on the dc reversal rate, in one case showing a variation of more than 0.1 μΩ/Ω for cycle times between 10 s and 1000 s. Even in the best cases, effects of at least 0.01 μΩ/Ω are present. Furthermore, the assumption that the apparent resistance value converges to a limiting value for long waiting times after reversal is not always upheld, making it difficult to quote a simple dc value. Existing models of Peltier heating at wire junctions do not completely explain our observations. The problems presented have been the limiting factor for 1 Ω measurements as part of a recent on-site comparison of quantum Hall effect resistance standards.

  1. The effect of Non- ionizing electromagnetic field with a frequency of 50 Hz in Rat ovary: A transmission electron microscopy study

    PubMed Central

    Khaki, Amir Afshin; Khaki, Arash; Ahmadi, Seyed Shahin

    2016-01-01

    Background: Recently, there are increasing concerns and interests about the potential effects of Electromagnetic Field (EMF) on both human and animal health. Objective: The goal of this study was to evaluate the harmful effects of 50 Hz non-ionizing EMF on rat oocytes. Materials and Methods: In this experimental study 30 rats were randomly taken from laboratory animals and their ags and weights were determined. These 3 month's old rats were randomly divided into 3 groups. The control group consisted of 10 rats without receiving any treatment and kept under normal conditions. Experimental group 1 (10 rats) received EMF for 8 weeks (3 weeks intrauterine +5 weeks after births) and experimental group 2 (10 rats) received EMF for 13 weeks (3 weeks intrauterine +10 weeks after birth). After removing the ovaries and isolating follicles, granulosa cells were fixed in glutaraldehyde and osmium tetroxide. Electron microscopy was used to investigate the traumatic effects of EMF on follicles. Results: In control group nucleus membrane and mitochondria in follicle’s cytoplasm seemed normal in appearance. Theca layer of primary follicles in experimental group was separated clearly, zona layer demonstrated trot with irregular thickness and ovarian stroma seemed isolated with dilated vessels showing infiltration. Conclusion: According to the results of this study, it can be concluded that EMF has harmful effects on the ovarian follicles. PMID:27200427

  2. 44 CFR 10.12 - Pre-implementation actions.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 44 Emergency Management and Assistance 1 2014-10-01 2014-10-01 false Pre-implementation actions. 10.12 Section 10.12 Emergency Management and Assistance FEDERAL EMERGENCY MANAGEMENT AGENCY... integrated into the decision-making process. Because of the diversity of FEMA, it is not feasible to...

  3. 44 CFR 10.12 - Pre-implementation actions.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 44 Emergency Management and Assistance 1 2011-10-01 2011-10-01 false Pre-implementation actions. 10.12 Section 10.12 Emergency Management and Assistance FEDERAL EMERGENCY MANAGEMENT AGENCY... integrated into the decision-making process. Because of the diversity of FEMA, it is not feasible to...

  4. 44 CFR 10.12 - Pre-implementation actions.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 44 Emergency Management and Assistance 1 2012-10-01 2011-10-01 true Pre-implementation actions. 10.12 Section 10.12 Emergency Management and Assistance FEDERAL EMERGENCY MANAGEMENT AGENCY, DEPARTMENT... decision-making process. Because of the diversity of FEMA, it is not feasible to describe in this part...

  5. Development of chick embryos in 1 Hz to 100 kHz magnetic fields.

    PubMed

    Juutilainen, J; Saali, K

    1986-01-01

    Chick embryos were exposed during their 48 first hours of development to sinusoidally oscillating magnetic fields. The frequencies 1 Hz, 10 Hz, 16.7 Hz, 30 Hz, 50 Hz, 1 kHz, 10 kHz and 100 kHz, and the field strengths 0.1, 1, 10 and 100 A/m were used. Each exposure group consisted of 20 eggs. After the exposure, the embryos were examined for abnormalities and classified by the developmental stage. The percentage of abnormal embryos (%AE) was significantly increased at frequencies from 16.7 Hz to 100 kHz. Above a threshold field strength of about 0.1 to 1 A/m, %AE was rather independent of the field strength, varying from 16% to 56% in different exposure groups. 13% of the sham-exposed control embryos (n = 150) were abnormal. Only the 0.1 A/m exposure group differed significantly from the controls at 1 Hz, and no significant effect was found at 10 Hz. The developmental stage was in general not affected by the magnetic fields, but some abnormal embryos showed retarded development.

  6. Energetic Particle Propagation in the Inner Heliosphere as Deduced from Low Frequency (less than 100 kHz) Observations of Type III Radio Bursts

    NASA Technical Reports Server (NTRS)

    Cane, H. V.; Erickson, W. C.

    2003-01-01

    Solar energetic particle (SEP) events are well-associated with solar flares. It is observed that the delay between the time of the flare and the first-arriving particles at a spacecraft increases with increasing difference between the flare longitude and the footpoint of the field line on which the spacecraft is located. This difference we call the "connection angle" and can be as large as approximately 120 deg. Recently it has been found that all SEP events are preceded by type III radio bursts. These bursts are plasma emission caused by the propagation of 2-50 keV flare electrons through the solar corona and into the solar wind. The drift of these type III radio bursts to lower and lower frequencies enables the propagation of the flare electrons to be traced from the Sun to about 1 AU. We have made an extensive analysis of the type III bursts associated with greater than 20 MeV proton events and find that, in most cases, the radio emission extends to the local plasma frequency when the energetic particles arrive within a few hours of the flare. We conclude that this emission at the lowest possible frequency is generated close to the spacecraft. We then use the time from when the burst started at the Sun to when it reached the local plasma frequency to infer the time it took the radio producing electrons to travel to the spacecraft. We find that these delay times are organized by the connection angle and correlate with the proton delay times. We also find that the differences between the radio delays at Wind and Ulysses are matched by differences in the relative arrival times of the energetic particles at the two spacecraft. The consistent timing between the relative arrival times of energetic electrons and protons and the start of the lowest frequency radio emissions suggests that the first arriving particles of both species are accelerated as part of the flare process and that they propagate to the spacecraft along trajectories similar to those of the lower

  7. All-sky coherent search for continuous gravitational waves in 6-7 Hz band with a torsion-bar antenna

    NASA Astrophysics Data System (ADS)

    Eda, Kazunari; Shoda, Ayaka; Kuwahara, Yuya; Itoh, Yousuke; Ando, Masaki

    2016-01-01

    A torsion-bar antenna (TOBA) is a low-frequency terrestrial gravitational wave (GW) antenna which consists of two orthogonal bar-shaped test masses. We upgraded the prototype TOBA and achieved the strain sensitivity 10^{-10} Hz^{-1/2} at around 1 Hz. We operated the upgraded TOBA (called the "Phase-II TOBA") located at Tokyo in Japan for 22.5 hours and performed an all-sky coherent search for continuous GWs using the mathcal {F}-statistic. We place upper limits on continuous GWs from electromagnetically unknown sources in the frequency range from 6 Hz to 7 Hz with the first derivative of frequency less than 7.62 × 10^{-11} Hz s^{-1} using data from the TOBA. As a result, no significant GW signals are found in the frequency band 6-7 Hz. The strictest upper limit on the dimensionless GW strain with a 95% confidence level in this band is 3.6 × 10^{-12} at 6.84 Hz.

  8. 10 Hz flicker improves recognition memory in older people

    PubMed Central

    Williams, Jonathan; Ramaswamy, Deepa; Oulhaj, Abderrahim

    2006-01-01

    Background 10 Hz electroencephalographic (EEG) alpha rhythms correlate with memory performance. Alpha and memory decline in older people. We wished to test if alpha-like EEG activity contributes to memory formation. Flicker can elicit alpha-like EEG activity. We tested if alpha-frequency flicker enhances memory in older people. Pariticpants aged 67–92 identified short words that followed 1 s of flicker at 9.0 Hz, 9.5 Hz, 10.0 Hz, 10.2 Hz, 10.5 Hz, 11.0 Hz, 11.5 Hz or 500 Hz. A few minutes later, we tested participants' recognition of the words (without flicker). Results Flicker frequencies close to 10 Hz (9.5–11.0 Hz) facilitated the identification of the test words in older participants. The same flicker frequencies increased recognition of the words more than other frequencies (9.0 Hz, 11.5 Hz and 500 Hz), irrespective of age. Conclusion The frequency-specificity of flicker's effects in our participants paralleled the power spectrum of EEG alpha in the general population. This indicates that alpha-like EEG activity may subserve memory processes. Flicker may be able to help memory problems in older people. PMID:16515710

  9. Low-frequency ultrasound (20-40 kHz) as an adjunctive therapy for chronic wound healing: a systematic review of the literature and meta-analysis of eight randomized controlled trials.

    PubMed

    Voigt, Jeffrey; Wendelken, Martin; Driver, Vickie; Alvarez, Oscar M

    2011-12-01

    Ultrasound as a therapeutic agent in chronic wound healing has been studied extensively. This systematic review and meta-analysis specifically examines low-frequency (20-30 kHz) ultrasound delivered at either low or high intensity. The objective of this review was to determine whether low-frequency ultrasound used as an adjunctive therapy improves the outcomes of complete healing and reduction of size of chronic lower limb wounds. PubMed, Cochrane/CENTRAL, technical assessment, relevant wound-related journals, and clinical guidelines were searched along with contacting manufacturers and authors of relevant randomized controlled trials were completed. Searches focused on the use of low-frequency ultrasound in randomized controlled trials. Data were collected via a data collection form and was adjudicated independently via coauthors. Meta-analyses and heterogeneity checks were performed using Mantel-Haenszel and inverse variance (fixed and random effects) statistical methods on studies with similar outcomes (complete healing and percent wound area reduction) over similar time periods. Single study results were reported via the statistical methods used in the study. Eight randomized controlled trials were identified. Results demonstrated that early healing (at ≤5 months) in patients with venous stasis and diabetic foot ulcers was favorably influenced by both high- and low-intensity ultrasound delivered at a low frequency-either via contact or noncontact techniques. However, the quality of the data may be suspect, especially for low-frequency low-intensity noncontact ultrasound because of significant biases. In patients presenting with either venous stasis or diabetic foot ulcers (Wagner classification 1-3), early healing appears to be facilitated by either low-frequency low-intensity noncontact ultrasound or low-frequency high-intensity contact ultrasound.

  10. Assessment of the neurotoxic potential of exposure to 50Hz extremely low frequency electromagnetic fields (ELF-EMF) in naïve and chemically stressed PC12 cells.

    PubMed

    de Groot, Martje W G D M; Kock, Marjolijn D M; Westerink, Remco H S

    2014-09-01

    Increasing exposure to extremely low frequency electromagnetic fields (ELF-EMF), generated by power lines and electric appliances, raises concern about potential adverse health effects of ELF-EMF. The central nervous system is expected to be particularly vulnerable to ELF-EMF as its function strongly depends on electrical excitability. We therefore investigated effects of acute (30min) and sub-chronic (48h) exposure to 50Hz ELF-EMF on naïve and chemically stressed pheochromocytoma (PC12) cells. The latter have higher levels of iron and/or reactive oxygen species (ROS) and display increased vulnerability to environmental insults. Effects of ELF-EMF on Ca(2+)-homeostasis, ROS production and membrane integrity were assessed using Fura-2 single cell fluorescence microscopy, H2-DCFDA and CFDA assays, respectively. Our data demonstrate that acute exposure of naïve PC12 cells to 50Hz ELF-EMF up to 1000μT fails to affect basal or depolarization-evoked [Ca(2+)]i. Moreover, sub-chronic ELF-EMF exposure up to 1000μT has no consistent effects on Ca(2+)-homeostasis in naïve PC12 cells and does not affect ROS production and membrane integrity. Notably, in chemically stressed PC12 cells both acute and sub-chronic ELF-EMF exposure also failed to exert consistent effects on Ca(2+)-homeostasis, ROS production and membrane integrity. Our combined findings thus indicate that exposure to 50Hz ELF-EMF up to 1000μT, i.e. 10,000 times above background exposure, does not induce neurotoxic effects in vitro, neither in naïve nor in chemically stressed PC12 cells. Though our data require confirmation, e.g. in developing neuronal cells in vitro or (developing) animals, it appears that the neurotoxic risk of ELF-EMF exposure is limited.

  11. Anomalous Random Telegraph Signal Extractions from a Very Large Number of n-Metal Oxide Semiconductor Field-Effect Transistors Using Test Element Groups with 0.47 Hz-3.0 MHz Sampling Frequency

    NASA Astrophysics Data System (ADS)

    Abe, Kenichi; Fujisawa, Takafumi; Teramoto, Akinobu; Watabe, Shunichi; Sugawa, Shigetoshi; Ohmi, Tadahiro

    2009-04-01

    Random telegraph signal (RTS) noise in small gate area metal oxide semiconductor (MOS) transistors occurs frequently and causes serious problems in the field of flash memories and complementary MOS (CMOS) image sensors. The trap in the gate insulator, which is considered the origin of RTS, varies widely in terms of spatial location and energy level, so that RTS characteristics including the amplitude and time constants have large variability by nature and statistical analysis of RTS should become indispensable. In this paper, we propose a high-speed RTS measurement system with a newly developed test circuit and discuss the drain current and temperature dependences of RTS amplitude distributions. Moreover, we expand the sampling frequency between 0.47 Hz-3.0 MHz and the observation length up to about 4 h and can thereby observe some anomalous RTSs such as ones with long time constants, ones generated abruptly, and ones disappearing.

  12. Stabilization of sample temperature in a surface-science vacuum chamber to 0.03 K and quartz-crystal microbalance frequency to 0.06 Hz over 0.5 h

    SciTech Connect

    Slavin, Alan J.

    2010-10-15

    Improvements have been made to a high-stability quartz-crystal microbalance for use in a typical surface-science, ultrahigh vacuum chamber, with a frequency stability of one part in 10{sup 8} (0.06 Hz) over 0.5 h. This gives a resolution equivalent to 2% of an atomic monolayer of oxygen over 0.5 h. The quartz-crystal microbalance (QCM) crystal can be rotated to different surface-analysis positions in the chamber. These characteristics open up the combination of surface and bulk adsorption studies on the same sample without transferring the sample to another chamber. To accomplish this, it was necessary to stabilize the sample temperature to {+-}0.03 K over several hours. The oscillator performance is illustrated by the uptake of oxygen by a gold-plated QCM crystal.

  13. Modification of the ultrasound induced activity by the presence of an electrode in a sonoreactor working at two low frequencies (20 and 40 kHz). Part I: Active zone visualization by laser tomography.

    PubMed

    Mandroyan, A; Viennet, R; Bailly, Y; Doche, M-L; Hihn, J-Y

    2009-01-01

    Sonoelectrochemical experiments differ from sonochemical ones by the introduction of electrodes in the sonicated reaction vessel. The aim of the study is to characterize the changes of the ultrasonic activity induced by the presence of an electrode located in front of the transducer. The scope of our investigations concerns two low frequencies vibration modes: 20 and 40 kHz. For this purpose, two laser visualization techniques have been used. The first part of the study, described in the present paper (part I), deals with the laser tomography technique which provides an accurate picture of the reactor actives zones, related to numerous cavitation events. For each frequency, two parameters were studied: the electrical power supplied to the transducer and the electrode transducer distance. At both frequencies, without electrode, we can observe distinct zones corresponding to cavitation production and stationary waves establishment. When increasing the input power, bubble clouds tend to form a unique cloud near the transducer. In presence of the electrode, bubble cavitation clouds are largely influenced by the obstacle. The second part of the paper (part II) will describe the Particle Image Velocimetry (P.I.V.) technique which allows to measure the velocity vector field in the fluid portion between the horn and the electrode.

  14. Music, Grades 10-12. Secondary Schools Curriculum Guide.

    ERIC Educational Resources Information Center

    Cranston School Dept., RI.

    Nine courses are included in this music guide for grades 10-12: Music Theory; Humanities: Renaissance, Baroque, and Classical; Humanities: Idealism vs. Realism; Humanities: 20th Century Man and His World; A Capella Choir; Chorale; Band; and Basic Keyboard Study. Major objectives, numbered objectives, and activities indicate level of learning,…

  15. Career Education Resource Guide. Volume III: 10-12.

    ERIC Educational Resources Information Center

    Treacy, Thomas D., Ed.

    This third of a three-volume career education resource guide consists of 146 teacher-developed and -tested learning activities for use in grades 10-12. Included in this volume are activities that can be incorporated into existing curricula in the following subject areas: art, biology, business, chemistry, English, foreign languages, counseling,…

  16. Social Studies, Grades 10-12. Secondary Schools Curriculum Guide.

    ERIC Educational Resources Information Center

    Cranston School Dept., RI.

    This curriculum guide provides a one-year course in social studies for grades 10-12. The guide is intended to serve as a resource to teachers, students, department chairmen, guidance personnel, curriculum planners, and anyone else involved in present or future curriculum planning. The course is divided into 22 section areas covering the topics of…

  17. Newspapers and Law-Related Education. Grades 10-12.

    ERIC Educational Resources Information Center

    Diamond, Sandra; Riekes, Linda

    Designed to assist teachers of students in grades 10-12 who wish to use the newspaper as a supplemental tool in law-related education, this guide provides model lessons demonstrating ways in which the daily newspaper can enhance textbook material. Although the guide is based on ongoing law-related education programs in St. Louis Public Schools, it…

  18. 47 CFR 80.882 - 2182 kHz watch.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false 2182 kHz watch. 80.882 Section 80.882 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES STATIONS IN THE... kHz watch. Ships subject to this subpart must maintain a watch on the frequency 2182 kHz pursuant...

  19. 47 CFR 80.882 - 2182 kHz watch.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false 2182 kHz watch. 80.882 Section 80.882 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES STATIONS IN THE... kHz watch. Ships subject to this subpart must maintain a watch on the frequency 2182 kHz pursuant...

  20. 47 CFR 80.882 - 2182 kHz watch.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false 2182 kHz watch. 80.882 Section 80.882 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES STATIONS IN THE... kHz watch. Ships subject to this subpart must maintain a watch on the frequency 2182 kHz pursuant...

  1. 47 CFR 80.882 - 2182 kHz watch.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false 2182 kHz watch. 80.882 Section 80.882 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES STATIONS IN THE... kHz watch. Ships subject to this subpart must maintain a watch on the frequency 2182 kHz pursuant...

  2. 47 CFR 80.882 - 2182 kHz watch.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false 2182 kHz watch. 80.882 Section 80.882 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES STATIONS IN THE... kHz watch. Ships subject to this subpart must maintain a watch on the frequency 2182 kHz pursuant...

  3. Low frequency ultrasound (42 kHz) assisted degradation of Acid Blue 113 in the presence of visible light driven rare earth nanoclusters loaded TiO2 nanophotocatalysts.

    PubMed

    Sathishkumar, Panneerselvam; Mangalaraja, Ramalinga Viswanathan; Rozas, Oscar; Mansilla, Héctor D; Gracia-Pinilla, M A; Anandan, Sambandam

    2014-09-01

    An attempt has been made to render the visible light driven photocatalytic activity to the TiO2 nanocatalysts by loading 1 wt% of rare earth (RE) nanoclusters (Gd(3+), Nd(3+) and Y(3+)) using a low frequency (42 kHz) producing commercial sonicator. The STEM-HAADF analysis confirms that the RE nanoclusters were residing at the surface of the TiO2. Transmission electron microscopic (TEM) and X-ray diffraction (XRD) analyses confirm that the loading of RE nanoclusters cannot make any significant changes in the crystal structure of TiO2. However, the optical properties of the resulted nanocatalysts were significantly modified and the nanocatalysts were employed to study the sonocatalytic, photocatalytic and sonophotocatalytic decolorization as well as mineralization of Acid Blue 113 (AB113). Among the experimented nanocatalysts maximum degradation of AB113 was achieved in the presence Y(3+)-TiO2 nanocatalysts. The decolorization of AB113 in the presence and absence of Y(3+) loaded TiO2 ensues the following order sonolysis

  4. Enhanced therapeutic anti-inflammatory effect of betamethasone upon topical administration with low frequency, low intensity (20 kHz, 100 mW/cm2) ultrasound exposure on carrageenan-induced arthritis in mice model

    PubMed Central

    Cohen, Gadi; Natsheh, Hiba; Sunny, Youhan; Bawiec, Christopher R.; Touitou, Elka; Lerman, Melissa A.; Lazarovici, Philip; Lewin, Peter A.

    2015-01-01

    The purpose of this work was to investigate whether low frequency, low intensity (LFLI, 20 kHz, <100 mW/cm2, spatial-peak, temporal-peak) ultrasound (US), delivered by a light-weight (<100g), tether-free, fully wearable, battery powered applicator is capable of reducing inflammation in a mouse model of Rheumatoid Arthritis (RA). The therapeutic, acute, anti-inflammatory effect was estimated by the relative swelling induced in mice hind limb paws. In an independent, indirect approach, the inflammation was bio-imaged by measuring glycolytic activity with near infrared labeled 2-deoxy-glucose (2DG). The outcome of the experiments indicated that the combination of US exposure with topical application of 0.1% w/w betamethasone gel, exhibited statistically significant (p<0.05) enhanced anti-inflammatory properties in comparison with the drug or US treatment alone. The present study underscores the potential benefits of LFLI US assisted drug delivery. However, the proof of concept presented indicates the need for additional experiments to systematically evaluate and optimize the potential of, and the conditions for, safe, LFLI ultrasound promoted non-invasive drug delivery. PMID:26003010

  5. Low frequency ultrasound (42 kHz) assisted degradation of Acid Blue 113 in the presence of visible light driven rare earth nanoclusters loaded TiO2 nanophotocatalysts.

    PubMed

    Sathishkumar, Panneerselvam; Mangalaraja, Ramalinga Viswanathan; Rozas, Oscar; Mansilla, Héctor D; Gracia-Pinilla, M A; Anandan, Sambandam

    2014-09-01

    An attempt has been made to render the visible light driven photocatalytic activity to the TiO2 nanocatalysts by loading 1 wt% of rare earth (RE) nanoclusters (Gd(3+), Nd(3+) and Y(3+)) using a low frequency (42 kHz) producing commercial sonicator. The STEM-HAADF analysis confirms that the RE nanoclusters were residing at the surface of the TiO2. Transmission electron microscopic (TEM) and X-ray diffraction (XRD) analyses confirm that the loading of RE nanoclusters cannot make any significant changes in the crystal structure of TiO2. However, the optical properties of the resulted nanocatalysts were significantly modified and the nanocatalysts were employed to study the sonocatalytic, photocatalytic and sonophotocatalytic decolorization as well as mineralization of Acid Blue 113 (AB113). Among the experimented nanocatalysts maximum degradation of AB113 was achieved in the presence Y(3+)-TiO2 nanocatalysts. The decolorization of AB113 in the presence and absence of Y(3+) loaded TiO2 ensues the following order sonolysis

  6. Watts linkage based large band low frequency sensors for scientific applications

    NASA Astrophysics Data System (ADS)

    Barone, F.; Giordano, G.; Acernese, F.; Romano, R.

    2016-07-01

    The UNISA Folded Pendulum class of horizontal and vertical sensors, based on an innovative configuration of the classical Watt's linkage mechanical architecture, allows the design and implementation of very large band monolithic sensors (10-7 Hz to102 Hz), whose sensitivities for the most common applications are defined by the noise introduced by their readouts (e.g. <10-12 m /√{ Hz } with classical LVDT readouts). These unique features, coupled other relevant properties like scalability, compactness, lightness, high directivity, frequency tunability (typical resonance frequencies in the band 10-1 Hz to102 Hz), very high immunity to environmental noises and low cost make this class of sensors very effective for the implementation of uniaxial (horizontal and/or vertical) and triaxial seismometers and accelerometers for ground, space and underwater applications, including UHV and cryogenics ones.

  7. Ambient noise measurements from 100 Hz to 80 kHz in an Alaskan fjord.

    PubMed

    McConnell, S O; Schilt, M P; Dworski, J G

    1992-04-01

    Measurements covering a broad frequency range from 100 Hz to 80 kHz have been made in Behm Canal, Alaska. This site represents a fairly deep embayment (400 m) with a soft bottom (porosity of about 0.8) and, hence, the noise detected at the hydrophones is affected negligibly by multipath contributions except possibly at the lowest frequencies. Data were gathered over a wide range of wind speeds (0 to 15 m/s) and during periods of rain and snow. Several unique and noteworthy results were obtained. Foremost was the observation that the wind-generated noise level measured during the winter was approximately 5 dB lower than during the summer for the same wind speeds and air-sea temperature differences (air temperature about the same as or colder than the sea surface). The summer data agree well with the most recent published measurements and are approximately 2 dB higher than the standard Knudsen/Wenz reference spectra. It appeared that below-freezing air temperatures and snow were responsible for the 5 dB offset between the summer and winter data. Most reported wind noise measurements are restricted to frequencies less than 20 kHz. Those that go beyond this frequency display a noticeable hump above the usual--17 dB/decade power-law slope, and the Behm Canal measurements show that this hump continues to 80 kHz where the spectrum rejoins the extension of the canonical power-law slope.

  8. RHIC 10 Hz global orbit feedback system

    SciTech Connect

    Michnoff, R.; Arnold, L.; Carboni, L.; Cerniglia, P; Curcio, A.; DeSanto, L.; Folz, C.; Ho, C.; Hoff, L.; Hulsart, R.; Karl, R.; Luo, Y.; Liu, C.; MacKay, W.; Mahler, G.; Meng, W.; Mernick, K.; Minty, M.; Montag, C.; Olsen, R.; Piacentino, J.; Popken, P.; Przybylinski, R.; Ptitsyn, V.; Ritter, J.; Schoenfeld, R.; Thieberger, P.; Tuozzolo, J.; Weston, A.; White, J.; Ziminski, P.; Zimmerman, P.

    2011-03-28

    Vibrations of the cryogenic triplet magnets at the Relativistic Heavy Ion Collider (RHIC) are suspected to be causing the horizontal beam perturbations observed at frequencies around 10 Hz. Several solutions to counteract the effect have been considered in the past, including a local beam feedback system at each of the two experimental areas, reinforcing the magnet base support assembly, and a mechanical servo feedback system. However, the local feedback system was insufficient because perturbation amplitudes outside the experimental areas were still problematic, and the mechanical solutions are very expensive. A global 10 Hz orbit feedback system consisting of 36 beam position monitors (BPMs) and 12 small dedicated dipole corrector magnets in each of the two 3.8 km circumference counter-rotating rings has been developed and commissioned in February 2011. A description of the system architecture and results with beam will be discussed.

  9. Humans perceive flicker artifacts at 500 Hz

    NASA Astrophysics Data System (ADS)

    Davis, James; Hsieh, Yi-Hsuan; Lee, Hung-Chi

    2015-02-01

    Humans perceive a stable average intensity image without flicker artifacts when a television or monitor updates at a sufficiently fast rate. This rate, known as the critical flicker fusion rate, has been studied for both spatially uniform lights, and spatio-temporal displays. These studies have included both stabilized and unstablized retinal images, and report the maximum observable rate as 50-90 Hz. A separate line of research has reported that fast eye movements known as saccades allow simple modulated LEDs to be observed at very high rates. Here we show that humans perceive visual flicker artifacts at rates over 500 Hz when a display includes high frequency spatial edges. This rate is many times higher than previously reported. As a result, modern display designs which use complex spatio-temporal coding need to update much faster than conventional TVs, which traditionally presented a simple sequence of natural images.

  10. 50-kHz, 50-ns UV pulse generation by diode-pumped frequency doubling Pr3+:YLF Q-switch laser with a Cr4+:YAG saturable absorber.

    PubMed

    Tanaka, Hiroki; Kariyama, Ryosuke; Iijima, Kodai; Kannari, Fumihiko

    2016-08-10

    We demonstrate intracavity second-harmonic generation at 320 nm of a diode-pumped praseodymium-doped YLF laser Q-switched by a Cr4+:YAG crystal. By employing two 3.5-W high-power blue InGaN diode lasers as the pump source, we obtained 50-ns Q-switched pulses with a pulse energy of 1.54 μJ at a repetition rate of 50 kHz. A rate equation analysis shows good agreement with the experimental results. PMID:27534459

  11. Epilepsy provoked by television and video games: safety of 100-Hz screens.

    PubMed

    Ricci, S; Vigevano, F; Manfredi, M; Kasteleijn-Nolst Trenité, D G

    1998-03-01

    Television (TV) and video games (VG) can provoke seizures in patients with photosensitive epilepsies. Flicker frequency is the most important factor in screen activation. We tested conventional 50-Hz versus 100-Hz monitors during TV viewing and VG playing in 30 photosensitive subjects, 23 of whom had a history of TV or VG seizures or both. Fifteen subjects' discharges were activated by 50-Hz TV; 17 by 50-Hz VG; and one by a 100-Hz screen. Thus, 100-Hz screens protect against screen activation. PMID:9521278

  12. Epilepsy provoked by television and video games: safety of 100-Hz screens.

    PubMed

    Ricci, S; Vigevano, F; Manfredi, M; Kasteleijn-Nolst Trenité, D G

    1998-03-01

    Television (TV) and video games (VG) can provoke seizures in patients with photosensitive epilepsies. Flicker frequency is the most important factor in screen activation. We tested conventional 50-Hz versus 100-Hz monitors during TV viewing and VG playing in 30 photosensitive subjects, 23 of whom had a history of TV or VG seizures or both. Fifteen subjects' discharges were activated by 50-Hz TV; 17 by 50-Hz VG; and one by a 100-Hz screen. Thus, 100-Hz screens protect against screen activation.

  13. 47 CFR 15.219 - Operation in the band 510-1705 kHz.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 1 2014-10-01 2014-10-01 false Operation in the band 510-1705 kHz. 15.219... kHz. (a) The total input power to the final radio frequency stage (exclusive of filament or heater... ground lead (if used) shall not exceed 3 meters. (c) All emissions below 510 kHz or above 1705 kHz...

  14. 47 CFR 15.219 - Operation in the band 510-1705 kHz.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 1 2011-10-01 2011-10-01 false Operation in the band 510-1705 kHz. 15.219... kHz. (a) The total input power to the final radio frequency stage (exclusive of filament or heater... ground lead (if used) shall not exceed 3 meters. (c) All emissions below 510 kHz or above 1705 kHz...

  15. 47 CFR 15.219 - Operation in the band 510-1705 kHz.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false Operation in the band 510-1705 kHz. 15.219... kHz. (a) The total input power to the final radio frequency stage (exclusive of filament or heater... ground lead (if used) shall not exceed 3 meters. (c) All emissions below 510 kHz or above 1705 kHz...

  16. 47 CFR 15.219 - Operation in the band 510-1705 kHz.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 1 2013-10-01 2013-10-01 false Operation in the band 510-1705 kHz. 15.219... kHz. (a) The total input power to the final radio frequency stage (exclusive of filament or heater... ground lead (if used) shall not exceed 3 meters. (c) All emissions below 510 kHz or above 1705 kHz...

  17. 47 CFR 15.219 - Operation in the band 510-1705 kHz.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 1 2012-10-01 2012-10-01 false Operation in the band 510-1705 kHz. 15.219... kHz. (a) The total input power to the final radio frequency stage (exclusive of filament or heater... ground lead (if used) shall not exceed 3 meters. (c) All emissions below 510 kHz or above 1705 kHz...

  18. Sustained Effectiveness of 10 kHz High-Frequency Spinal Cord Stimulation for Patients with Chronic, Low Back Pain: 24-Month Results of a Prospective Multicenter Study

    PubMed Central

    Al-Kaisy, Adnan; Van Buyten, Jean-Pierre; Smet, Iris; Palmisani, Stefano; Pang, David; Smith, Thomas

    2014-01-01

    Objective The aim of this study was to investigate the long-term efficacy and safety of paresthesia-free high-frequency spinal cord stimulation (HF10 SCS) for the treatment of chronic, intractable pain of the low back and legs. Design Prospective, multicenter, observational study. Method Patients with significant chronic low back pain underwent implantation of a spinal cord stimulator capable of HF10 SCS. Patients' pain ratings, disability, sleep disturbances, opioid use, satisfaction, and adverse events were assessed for 24 months. Results After a trial period, 88% (72 of 82) of patients reported a significant improvement in pain scores and underwent the permanent implantation of the system. Ninety percent (65 of 72) of patients attended a 24-month follow-up visit. Mean back pain was reduced from 8.4 ± 0.1 at baseline to 3.3 ± 0.3 at 24 months (P < 0.001), and mean leg pain from 5.4 ± 0.4 to 2.3 ± 0.3 (P < 0.001). Concomitantly to the pain relief, there were significant decreases in opioid use, Oswestry Disability Index score, and sleep disturbances. Patients' satisfaction and recommendation ratings were high. Adverse Events were similar in type and frequency to those observed with traditional SCS systems. Conclusions In patients with chronic low back pain, HF10 SCS resulted in clinically significant and sustained back and leg pain relief, functional and sleep improvements, opioid use reduction, and high patient satisfaction. These results support the long-term safety and sustained efficacy of HF10 SCS. PMID:24308759

  19. Neural coding of sound frequency by cricket auditory receptors.

    PubMed

    Imaizumi, K; Pollack, G S

    1999-02-15

    Crickets provide a useful model to study neural processing of sound frequency. Sound frequency is one parameter that crickets use to discriminate between conspecific signals and sounds made by predators, yet little is known about how frequency is represented at the level of auditory receptors. In this paper, we study the physiological properties of auditory receptor fibers (ARFs) by making single-unit recordings in the cricket Teleogryllus oceanicus. Characteristic frequencies (CFs) of ARFs are distributed discontinuously throughout the range of frequencies that we investigated (2-40 kHz) and appear to be clustered around three frequency ranges (10-12, and >/=18 kHz). A striking characteristic of cricket ARFs is the occurrence of additional sensitivity peaks at frequencies other than CFs. These additional sensitivity peaks allow crickets to detect sound over a wide frequency range, although the CFs of ARFs cover only the frequency bands mentioned above. To the best of our knowledge, this is the first example of the extension of an animal's hearing range through multiple sensitivity peaks of auditory receptors.

  20. NASA Rat Acoustic Tolerance Test 1994-1995: 8 kHz, 16 kHz, 32 kHz Experiments

    NASA Technical Reports Server (NTRS)

    Mele, Gary D.; Holley, Daniel C.; Naidu, Sujata

    1996-01-01

    Adult male Sprague-Dawley rats were exposed to chronic applied sound (74 to 79 dB, SPL) with octave band center frequencies of either 8, 16 or 32 kHz for up to 60 days. Control cages had ambient sound levels of about 62 dB (SPL). Groups of rats (test vs. control; N=9 per group) were euthanized after 0. 5. 14, 30, and 60 days. On each euthanasia day, objective evaluation of their physiology and behavior was performed using a Stress Assessment Battery (SAB) of measures. In addition, rat hearing was assessed using the brain stem auditory evoked potential (BAER) method after 60 days of exposure. No statistically significant differences in mean daily food use could be attributed to the presence of the applied test sound. Test rats used 5% more water than control rats. In the 8 kHz and 32 kHz tests this amount was statistically significant(P less than .05). This is a minor difference of questionable physiological significance. However, it may be an indication of a small reaction to the constant applied sound. Across all test frequencies, day 5 test rats had 6% larger spleens than control rats. No other body or organ weight differences were found to be statistically significant with respect to the application of sound. This spleen effect may be a transient adaptive process related to adaptation to the constant applied noise. No significant test effect on differential white blood cell counts could be demonstrated. One group demonstrated a low eosinophil count (16 kHz experiment, day 14 test group). However this was highly suspect. Across all test frequencies studied, day 5 test rats had 17% fewer total leukocytes than day 5 control rats. Sound exposed test rats exhibited 44% lower plasma corticosterone concentrations than did control rats. Note that the plasma corticosterone concentration was lower in the sound exposed test animals than the control animals in every instance (frequency exposure and number of days exposed).

  1. Optical Frequency Standards Based on Neutral Atoms and Molecules

    NASA Astrophysics Data System (ADS)

    Riehle, Fritz; Helmcke, Juergen

    The current status and prospects of optical frequency standards based on neutral atomic and molecular absorbers are reviewed. Special attention is given to an optical frequency standard based on cold Ca atoms which are interrogated with a pulsed excitation scheme leading to resolved line structures with a quality factor Q > 10^12. The optical frequency was measured by comparison with PTB's primary clock to be νCa = 455 986 240 494.13 kHz with a total relative uncertainty of 2.5 x10^-13. After a recent recommendation of the International Committee of Weights and Measures (CIPM), this frequency standard now represents one of the most accurate realizations of the length unit.

  2. The global distribution of natural and man-made ionospheric electric fields at 200 kHz and 540 kHz as observed by Ogo 6

    NASA Technical Reports Server (NTRS)

    Laaspere, T.; Semprebon, L. C.

    1974-01-01

    An experiment on the polar-orbiting Ogo 6 spacecraft yielded real-time analog data in several broadband channels and essentially continuous tape-recorded data from two narrow-band (200-Hz) receivers operating at 200 and 540 kHz. The results show that the worldwide distributions of signals at 200 and 540 kHz falls into a number of different categories: (1) naturally generated broadband (auroral) hiss at polar latitudes with typical 200-kHz intensities of around 0.1 microvolt per meter per Hz to the 1/2 power, maximum intensities of up to several microvolt per meter per Hz to the 1/2 power, and generally lower intensities at 540 kHz; (2) nighttime midlatitude enhancements of a few microvolts per meter, which probably result either from a superposition of signals from a number of 200- and 540-kHz stations or from interference from intense signals of much higher frequencies; (3) well-defined signal peaks associated with individual ground stations operating at 200 kHz; (4) striking signal enhancements in the conjugate region of a low-latitude 200-kHz station (Ashkhabad), suggesting propagation in the whistler mode to the opposite hemisphere; and (5) occasional signal enhancements at the magnetic equator.

  3. Eyewitness identification accuracy and response latency: the unruly 10-12-second rule.

    PubMed

    Weber, Nathan; Brewer, Neil; Wells, Gary L; Semmler, Carolyn; Keast, Amber

    2004-09-01

    Data are reported from 3,213 research eyewitnesses confirming that accurate eyewitness identifications from lineups are made faster than are inaccurate identifications. However, consistent with predictions from the recognition and search literatures, the authors did not find support for the "10-12-s rule" in which lineup identifications faster than 10-12 s maximally discriminate between accurate and inaccurate identifications (D. Dunning & S. Perretta, 2002). Instead, the time frame that proved most discriminating was highly variable across experiments, ranging from 5 s to 29 s, and the maximally discriminating time was often unimpressive in its ability to sort accurate from inaccurate identifications. The authors suggest several factors that are likely to moderate the 10-12-s rule. PMID:15462616

  4. Comparison of the Effects of 1 Hz and 20 Hz rTMS on Motor Recovery in Subacute Stroke Patients

    PubMed Central

    Kim, Chul; Choi, Hee Eun; Lee, Byeong-Ju; Lee, Ki Hoon; Lim, Young-Joon

    2014-01-01

    Objective To compare the low frequency (1 Hz) repetitive transcranial magnetic stimulation (rTMS) with high frequency (20 Hz) rTMS on motor functional improvement of the affected upper extremity in subacute stroke patients. Methods Forty patients with subacute ischemic stroke participated in this study. The first group received 10 sessions of 20 Hz rTMS at ipsilesional M1 area and the other group received 10 sessions of 1 Hz rTMS at contralesional M1 area. Motor training of the hemiparetic hand was conducted after each rTMS train. All the patients received conventional occupational therapy immediately after each rTMS session. Manual function test (MFT), Fugl-Meyer Assessment scale (FMS), Modified Barthel Index (MBI), Brunnstrom recovery stage, and grip strength were used to assess motor function before, at the end of, and one month after the last session of rTMS. Results No adverse side effects were reported during the course of the experiment using rTMS. No significant difference in motor function of the affected upper extremity was observed between the two groups before rTMS. Significant improvements in MFT, FMS, MBI, and Brunnstrom stage were observed in the both groups at the end of the last rTMS session and one month later (p<0.05). No significant difference was found between the two groups (p>0.05). Conclusion There was no significant difference in motor function of the affected upper extremity between 1 Hz and 20 Hz rTMS during the subacute period of ischemic stroke. Thus, we cannot conclude which has a greater effect. PMID:25379487

  5. Low frequency, high sensitive tunable mechanical monolithic horizontal sensors

    NASA Astrophysics Data System (ADS)

    Acernese, Fausto; De Rosa, Rosario; Giordano, Gerardo; Romano, Rocco; Vilasi, Silvia; Barone, Fabrizio

    2011-04-01

    This paper describes an optimized version of the mechanical version of the monolithic tunable folded pendulum, developed at the University of Salerno, configurable both as seismometer and, in a force-feedback configuration, as accelerometer. Typical application of the sensors are in the field of geophysics, including the study of seismic and newtonian noise for characterization of suitable sites for underground interferometer for gravitational waves detection. The sensor, shaped with precision machining and electric-discharge-machining, like the previous version, is a very compact instrument, very sensitive in the low-frequency seismic noise band, with a very good immunity to environmental noises. Important characteristics are the tunability of the resonance frequency and the integrated laser optical readout, consisting of an optical lever and an interferometer. The theoretical sensitivity curves, largely improved due to a new design of the pendulum arms and of the electronics, are in a very good agreement with the measurements. The very large measurement band (10-6 +/- 10Hz) is couple to a very good sensitivity (10-12 m/√Hz in the band 0.1 +/- 10Hz), as seismometer. Prototypes of monolithic seismometers are already operational in selected sites around the world both to acquire seismic data for scientific analysis of seismic noise and to collect all the useful information to understand their performances in the very low frequency band (f < 1mHz). The results of the monolithic sensor as accelerometer (force feed-back configuration) are also presented and discussed. Particular relevance has their sensitivity that is better than 10-11 m/s2/√Hz in the band 0.1 +/- 10Hz. Finally, hypotheses are made on further developments and improvements of monolithic sensors.

  6. A Supplementary Program for Environmental Education, Art, Grade 10-12.

    ERIC Educational Resources Information Center

    Warpinski, Robert

    Presented in this teacher's guide for grades 10-12 are lesson plans and ideas for integrating art (drawing, painting, graphics, photography, and commercial art) and environmental education. Each lesson originates with a fundamental concept pertaining to the environment and states, in addition, its discipline area, subject area, and problem…

  7. A Supplementary Program for Environmental Education, Mathematics, Grade 10-12.

    ERIC Educational Resources Information Center

    Warpinski, Robert

    Presented in this teacher's guide for grades 10-12 are lesson plans and ideas for integrating mathematics and environmental education. Each lesson originates with a fundamental concept pertaining to the environment and states, in addition, its discipline area, subject area, and problem orientation. Following this, behavioral objectives and…

  8. Secondary School Curriculum Guide. Music. Grades 10-12. Draft Copy.

    ERIC Educational Resources Information Center

    Rogers, Arnold R., Ed.; And Others

    This draft curriculum guide provides curriculum materials that are organized into behavioral objectives with a scope and sequence. Divided by grade and levels, each section includes level objectives and suggested activities. To be covered in grades 10-12 are 5 levels of musical content. They are: 1) why man creates and how he perceives; 2) the…

  9. Eyewitness Identification Accuracy and Response Latency: The Unruly 10-12-Second Rule

    ERIC Educational Resources Information Center

    Weber, Nathan; Brewer, Neil; Wells, Gary L.; Semmler, Carolyn; Keast, Amber

    2004-01-01

    Data are reported from 3,213 research eyewitnesses confirming that accurate eyewitness identifications from lineups are made faster than are inaccurate identifications. However, consistent with predictions from the recognition and search literatures, the authors did not find support for the "10-12-s rule" in which lineup identifications faster…

  10. Brain-computer interface based on intermodulation frequency

    NASA Astrophysics Data System (ADS)

    Chen, Xiaogang; Chen, Zhikai; Gao, Shangkai; Gao, Xiaorong

    2013-12-01

    Objective. Most recent steady-state visual evoked potential (SSVEP)-based brain-computer interface (BCI) systems have used a single frequency for each target, so that a large number of targets require a large number of stimulus frequencies and therefore a wider frequency band. However, human beings show good SSVEP responses only in a limited range of frequencies. Furthermore, this issue is especially problematic if the SSVEP-based BCI takes a PC monitor as a stimulator, which is only capable of generating a limited range of frequencies. To mitigate this issue, this study presents an innovative coding method for SSVEP-based BCI by means of intermodulation frequencies. Approach. Simultaneous modulations of stimulus luminance and color at different frequencies were utilized to induce intermodulation frequencies. Luminance flickered at relatively large frequency (10, 12, 15 Hz), while color alternated at low frequency (0.5, 1 Hz). An attractive feature of the proposed method was that it would substantially increase the number of targets at a single flickering frequency by altering color modulated frequencies. Based on this method, the BCI system presented in this study realized eight targets merely using three flickering frequencies. Main results. The online results obtained from 15 subjects (14 healthy and 1 with stroke) revealed that an average classification accuracy of 93.83% and information transfer rate (ITR) of 33.80 bit min-1 were achieved using our proposed SSVEP-based BCI system. Specifically, 5 out of the 15 subjects exhibited an ITR of 40.00 bit min-1 with a classification accuracy of 100%. Significance. These results suggested that intermodulation frequencies could be adopted as steady responses in BCI, for which our system could be used as a practical BCI system.

  11. The 2 Hz and 15 Hz electroacupuncture induced reverse effect on autonomic function in healthy adult using a heart rate variability analysis

    PubMed Central

    Jia, Bor-An; Cheng, Chin-Yi; Lin, Yi-Wen; Li, Tsai-Chung; Liu, Hsu-Jan; Hsieh, Ching-Liang

    2011-01-01

    The purpose of the present study was to investigate effect of electro-acupuncture (EA) at different frequencies on autonomic function. Twenty healthy adult volunteers were studied, and underwent 4 sessions of EA (sham, 2 Hz, 15 Hz, and 50 Hz). Sham, 2 Hz, 15 Hz, and 50 Hz EA was applied to the bilateral Leg Three Li (足三里 zú sān lǐ, ST-36) and Upper Great Hollow (上巨虛 shàng jù xū, ST-37) acupoints. The intensity of electrical stimulation was adjusted to obtain visible twitching of the anterior tibial muscle about 2.0-2.5 mA except sham without electrical stimulation. The components of heart rate variability (HRV) and blood pressure were measured before EA (BLP), EA (EAP), and post-EA periods (PEP). The results indicated that the natural logarithmic high frequency power (lnHF) of HRV was greater during PEP than during the BLP in the 2 Hz EA sessions. The natural logarithmic low frequency power (lnLF) of HRV was greater during the PEP than during the BLP in 15 Hz EA sessions, suggesting that 2 Hz EA apply to Leg Three Li (足三里 zú sān lǐ, ST-36) and Upper Great Hollow (上巨虛 shàng jù xū, ST-37) acupoints increased vagal activity, whereas 15 Hz EA increased sympathetic activity. PMID:24716105

  12. Biotransformation of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) by denitrifying Pseudomonas sp. strain FA1.

    PubMed

    Bhushan, Bharat; Paquet, Louise; Spain, Jim C; Hawari, Jalal

    2003-09-01

    The microbial and enzymatic degradation of a new energetic compound, 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20), is not well understood. Fundamental knowledge about the mechanism of microbial degradation of CL-20 is essential to allow the prediction of its fate in the environment. In the present study, a CL-20-degrading denitrifying strain capable of utilizing CL-20 as the sole nitrogen source, Pseudomonas sp. strain FA1, was isolated from a garden soil. Studies with intact cells showed that aerobic conditions were required for bacterial growth and that anaerobic conditions enhanced CL-20 biotransformation. An enzyme(s) involved in the initial biotransformation of CL-20 was shown to be membrane associated and NADH dependent, and its expression was up-regulated about 2.2-fold in CL-20-induced cells. The rates of CL-20 biotransformation by the resting cells and the membrane-enzyme preparation were 3.2 +/- 0.1 nmol h(-1) mg of cell biomass(-1) and 11.5 +/- 0.4 nmol h(-1) mg of protein(-1), respectively, under anaerobic conditions. In the membrane-enzyme-catalyzed reactions, 2.3 nitrite ions (NO(2)(-)), 1.5 molecules of nitrous oxide (N(2)O), and 1.7 molecules of formic acid (HCOOH) were produced per reacted CL-20 molecule. The membrane-enzyme preparation reduced nitrite to nitrous oxide under anaerobic conditions. A comparative study of native enzymes, deflavoenzymes, and a reconstituted enzyme(s) and their subsequent inhibition by diphenyliodonium revealed that biotransformation of CL-20 is catalyzed by a membrane-associated flavoenzyme. The latter catalyzed an oxygen-sensitive one-electron transfer reaction that caused initial N denitration of CL-20. PMID:12957905

  13. Biotransformation of 2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-Hexaazaisowurtzitane (CL-20) by Denitrifying Pseudomonas sp. Strain FA1

    PubMed Central

    Bhushan, Bharat; Paquet, Louise; Spain, Jim C.; Hawari, Jalal

    2003-01-01

    The microbial and enzymatic degradation of a new energetic compound, 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20), is not well understood. Fundamental knowledge about the mechanism of microbial degradation of CL-20 is essential to allow the prediction of its fate in the environment. In the present study, a CL-20-degrading denitrifying strain capable of utilizing CL-20 as the sole nitrogen source, Pseudomonas sp. strain FA1, was isolated from a garden soil. Studies with intact cells showed that aerobic conditions were required for bacterial growth and that anaerobic conditions enhanced CL-20 biotransformation. An enzyme(s) involved in the initial biotransformation of CL-20 was shown to be membrane associated and NADH dependent, and its expression was up-regulated about 2.2-fold in CL-20-induced cells. The rates of CL-20 biotransformation by the resting cells and the membrane-enzyme preparation were 3.2 ± 0.1 nmol h−1 mg of cell biomass−1 and 11.5 ± 0.4 nmol h−1 mg of protein−1, respectively, under anaerobic conditions. In the membrane-enzyme-catalyzed reactions, 2.3 nitrite ions (NO2−), 1.5 molecules of nitrous oxide (N2O), and 1.7 molecules of formic acid (HCOOH) were produced per reacted CL-20 molecule. The membrane-enzyme preparation reduced nitrite to nitrous oxide under anaerobic conditions. A comparative study of native enzymes, deflavoenzymes, and a reconstituted enzyme(s) and their subsequent inhibition by diphenyliodonium revealed that biotransformation of CL-20 is catalyzed by a membrane-associated flavoenzyme. The latter catalyzed an oxygen-sensitive one-electron transfer reaction that caused initial N denitration of CL-20. PMID:12957905

  14. Splitting attention reduces temporal resolution from 7 Hz for tracking one object to <3 Hz when tracking three.

    PubMed

    Holcombe, Alex O; Chen, Wei-Ying

    2013-01-01

    Overall performance when tracking moving targets is known to be poorer for larger numbers of targets, but the specific effect on tracking's temporal resolution has never been investigated. We document a broad range of display parameters for which visual tracking is limited by temporal frequency (the interval between when a target is at each location and a distracter moves in and replaces it) rather than by object speed. We tested tracking of one, two, and three moving targets while the eyes remained fixed. Variation of the number of distracters and their speed revealed both speed limits and temporal frequency limits on tracking. The temporal frequency limit fell from 7 Hz with one target to 4 Hz with two targets and 2.6 Hz with three targets. The large size of this performance decrease implies that in the two-target condition participants would have done better by tracking only one of the two targets and ignoring the other. These effects are predicted by serial models involving a single tracking focus that must switch among the targets, sampling the position of only one target at a time. If parallel processing theories are to explain why dividing the tracking resource reduces temporal resolution so markedly, supplemental assumptions will be required.

  15. A 40-Hz Auditory Potential Recorded from the Human Scalp

    NASA Astrophysics Data System (ADS)

    Galambos, Robert; Makeig, Scott; Talmachoff, Peter J.

    1981-04-01

    Computer techniques readily extract from the brainwaves an orderly sequence of brain potentials locked in time to sound stimuli. The potentials that appear 8 to 80 msec after the stimulus resemble 3 or 4 cycles of a 40-Hz sine wave; we show here that these waves combine to form a single, stable, composite wave when the sounds are repeated at rates around 40 per sec. This phenomenon, the 40-Hz event-related potential (ERP), displays several properties of theoretical and practical interest. First, it reportedly disappears with surgical anesthesia, and it resembles similar phenomena in the visual and olfactory system, facts which suggest that adequate processing of sensory information may require cyclical brain events in the 30- to 50-Hz range. Second, latency and amplitude measurements on the 40-Hz ERP indicate it may contain useful information on the number and basilar membrane location of the auditory nerve fibers a given tone excites. Third, the response is present at sound intensities very close to normal adult thresholds for the audiometric frequencies, a fact that could have application in clinical hearing testing.

  16. XMM-Newton discovery of mHz quasi-periodic oscillations in the high-mass X-ray binary IGR J19140+0951

    NASA Astrophysics Data System (ADS)

    Sidoli, L.; Esposito, P.; Motta, S. E.; Israel, G. L.; Rodríguez Castillo, G. A.

    2016-08-01

    We report on the discovery of mHz quasi-periodic oscillations (QPOs) from the high-mass X-ray binary (HMXB) IGR J19140+0951, during a 40 ks XMM-Newton observation performed in 2015, which caught the source in its faintest state ever observed. At the start of the observation, IGR J19140+0951 was at a low flux of 2 × 10-12 erg cm-2 s-1 (2-10 keV; LX = 3 × 1033 erg s-1 at 3.6 kpc), then its emission rose reaching a flux ˜10 times higher, in a flare-like activity. The investigation of the power spectrum reveals the presence of QPOs, detected only in the second part of the observation, with a strong peak at a frequency of 1.46 ± 0.07 mHz, together with higher harmonics. The X-ray spectrum is highly absorbed (NH = 1023 cm-2), well fitted by a power law with a photon index in the range 1.2-1.8. The re-analysis of a Chandra archival observation shows a modulation at ˜0.17 ± 0.05 mHz, very likely the neutron-star spin period (although a QPO cannot be excluded). We discuss the origin of the 1.46 mHz QPO in the framework of both disc-fed and wind-fed HMXBs, favouring the quasi-spherical accretion scenario. The low flux observed by XMM-Newton leads to about three orders of magnitude the source dynamic range, overlapping with the one observed from Supergiant Fast X-ray Transients (SFXTs). However, since its duty cycle is not as low as in SFXTs, IGR J19140+0951 is an intermediate system between persistent supergiant HMXBs and SFXTs, suggesting a smooth transition between these two sub-classes.

  17. BOLD fractional contribution to resting-state functional connectivity above 0.1 Hz.

    PubMed

    Chen, Jingyuan E; Glover, Gary H

    2015-02-15

    Blood oxygen level dependent (BOLD) spontaneous signals from resting-state (RS) brains have typically been characterized by low-pass filtered timeseries at frequencies ≤ 0.1 Hz, and studies of these low-frequency fluctuations have contributed exceptional understanding of the baseline functions of our brain. Very recently, emerging evidence has demonstrated that spontaneous activities may persist in higher frequency bands (even up to 0.8 Hz), while presenting less variable network patterns across the scan duration. However, as an indirect measure of neuronal activity, BOLD signal results from an inherently slow hemodynamic process, which in fact might be too slow to accommodate the observed high-frequency functional connectivity (FC). To examine whether the observed high-frequency spontaneous FC originates from BOLD contrast, we collected RS data as a function of echo time (TE). Here we focus on two specific resting state networks - the default-mode network (DMN) and executive control network (ECN), and the major findings are fourfold: (1) we observed BOLD-like linear TE-dependence in the spontaneous activity at frequency bands up to 0.5 Hz (the maximum frequency that can be resolved with TR=1s), supporting neural relevance of the RSFC at a higher frequency range; (2) conventional models of hemodynamic response functions must be modified to support resting state BOLD contrast, especially at higher frequencies; (3) there are increased fractions of non-BOLD-like contributions to the RSFC above the conventional 0.1 Hz (non-BOLD/BOLD contrast at 0.4-0.5 Hz is ~4 times that at <0.1 Hz); and (4) the spatial patterns of RSFC are frequency-dependent. Possible mechanisms underlying the present findings and technical concerns regarding RSFC above 0.1 Hz are discussed.

  18. Humans perceive flicker artifacts at 500 Hz.

    PubMed

    Davis, James; Hsieh, Yi-Hsuan; Lee, Hung-Chi

    2015-02-03

    Humans perceive a stable average intensity image without flicker artifacts when a television or monitor updates at a sufficiently fast rate. This rate, known as the critical flicker fusion rate, has been studied for both spatially uniform lights, and spatio-temporal displays. These studies have included both stabilized and unstablized retinal images, and report the maximum observable rate as 50-90 Hz. A separate line of research has reported that fast eye movements known as saccades allow simple modulated LEDs to be observed at very high rates. Here we show that humans perceive visual flicker artifacts at rates over 500 Hz when a display includes high frequency spatial edges. This rate is many times higher than previously reported. As a result, modern display designs which use complex spatio-temporal coding need to update much faster than conventional TVs, which traditionally presented a simple sequence of natural images.

  19. Sounds in the ocean at 1-100 Hz.

    PubMed

    Wilcock, William S D; Stafford, Kathleen M; Andrew, Rex K; Odom, Robert I

    2014-01-01

    Very-low-frequency sounds between 1 and 100 Hz propagate large distances in the ocean sound channel. Weather conditions, earthquakes, marine mammals, and anthropogenic activities influence sound levels in this band. Weather-related sounds result from interactions between waves, bubbles entrained by breaking waves, and the deformation of sea ice. Earthquakes generate sound in geologically active regions, and earthquake T waves propagate throughout the oceans. Blue and fin whales generate long bouts of sounds near 20 Hz that can dominate regional ambient noise levels seasonally. Anthropogenic sound sources include ship propellers, energy extraction, and seismic air guns and have been growing steadily. The increasing availability of long-term records of ocean sound will provide new opportunities for a deeper understanding of natural and anthropogenic sound sources and potential interactions between them. PMID:23876176

  20. Sounds in the ocean at 1-100 Hz.

    PubMed

    Wilcock, William S D; Stafford, Kathleen M; Andrew, Rex K; Odom, Robert I

    2014-01-01

    Very-low-frequency sounds between 1 and 100 Hz propagate large distances in the ocean sound channel. Weather conditions, earthquakes, marine mammals, and anthropogenic activities influence sound levels in this band. Weather-related sounds result from interactions between waves, bubbles entrained by breaking waves, and the deformation of sea ice. Earthquakes generate sound in geologically active regions, and earthquake T waves propagate throughout the oceans. Blue and fin whales generate long bouts of sounds near 20 Hz that can dominate regional ambient noise levels seasonally. Anthropogenic sound sources include ship propellers, energy extraction, and seismic air guns and have been growing steadily. The increasing availability of long-term records of ocean sound will provide new opportunities for a deeper understanding of natural and anthropogenic sound sources and potential interactions between them.

  1. 600-Hz linewidth short-linear-cavity fiber laser.

    PubMed

    Mo, Shupei; Huang, Xiang; Xu, Shanhui; Li, Can; Yang, Changsheng; Feng, Zhouming; Zhang, Weinan; Chen, Dongdan; Yang, Zhongmin

    2014-10-15

    We proposed a short-linear-cavity (SLC) fiber laser based on a virtual-folded-ring (VFR) resonator and a fiber Bragg grating Fabry-Perot filter. Spatial hole burning effect was reduced by retarding the polarization state of the counter-propagating light waves utilizing the VFR structure. The photon lifetime of the resonator was extended due to the multi-reflection inside the FBG FP, which increased the intra-cavity power and relatively suppressed the contribution of phase diffusion from spontaneous emission. The relaxation oscillation frequency is around 160 kHz due to the slow light effect. The linewidth of the SLC fiber laser was measured to be less than 600 Hz.

  2. The 1983-84 Connecticut 45-Hz-band field-strength measurements

    NASA Astrophysics Data System (ADS)

    Bannister, P. R.

    1986-03-01

    Extremely low frequency (ELF) measurements are made of the transverse horizontal magnetic field strength received in Connecticut. The AN/BSR-1 receiver consists of an AN/UYK-20 minicomputer, a signal timing and interface unit (STIU), a rubidium frequency time standard, two magnetic tape recorders, and a preamplifier. The transmission source of these farfield (1.6-Mm range) measurements is the U.S. Navy's ELF Wisconsin Test Facility (WTF), located in the Chequamegon National Forest in north central Wisconsin, about 8 km south of the village of Clam Lake. The WTF consists of two 22.5-km antennas; one of which is situated approximately in the north-south (NS) direction and the other approximately in the east-west (EW) direction. Each antenna is grounded at both ends. The electrical axis of the WTF EW antenna is 11 deg east of north at 45 Hz and 14 deg east of north at 75Hz. The electrical axis of the WTF NS antenna is 11 deg east of north at 45 Hz and 14 deg east of north at 75 Hz. The WTF array can be steered electrically. Its radiated power is approximately 0.5 W at 45 Hz and 1 W at 75 Hz. This report will compare results of 45 Hz band data taken during 1983 to 1984 with previous 45 Hz band measurements.

  3. Tropical Cyclone Paka's Initial Explosive Development (10-12 December, 1997)

    NASA Technical Reports Server (NTRS)

    Rodgers, Edward B.; Halverson, Jeff; Simpson, Joanne; Olson, William; Pierce, Harold

    1999-01-01

    Convection associated with an equatorial westerly wind burst was first observed late November during the strong El Nino of 1997 at approximately 2000 km southwest of the Hawaiian Islands. This region of convection lead to the formation of twin tropical cyclones, one in the southern hemisphere named Pam and the other in the northern hemisphere named Paka. During the first week in December, tropical cyclone Paka, the system of concern, reached tropical storm stage as it moved rapidly westward at relatively low latitudes. During the 10-12 of December, Paka rapidly developed into a typhoon.

  4. The effect of 10 Hz transcranial alternating current stimulation (tACS) on corticomuscular coherence

    PubMed Central

    Wach, Claudia; Krause, Vanessa; Moliadze, Vera; Paulus, Walter; Schnitzler, Alfons; Pollok, Bettina

    2013-01-01

    Synchronous oscillatory activity at alpha (8–12 Hz), beta (13–30 Hz), and gamma (30–90 Hz) frequencies is assumed to play a key role for motor control. Corticomuscular coherence (CMC) represents an established measure of the pyramidal system's integrity. Transcranial alternating current stimulation (tACS) offers the possibility to modulate ongoing oscillatory activity. Behaviorally, 20 Hz tACS in healthy subjects has been shown to result in movement slowing. However, the neurophysiological changes underlying these effects are not entirely understood yet. The present study aimed at ascertaining the effects of tACS at 10 and 20 Hz in healthy subjects on CMC and local power of the primary sensorimotor cortex. Neuromagnetic activity was recorded during isometric contraction before and at two time points (2–10 min and 30–38 min) after tACS of the left primary motor cortex (M1), using a 306 channel whole head magnetoencephalography (MEG) system. Additionally, electromyography (EMG) of the right extensor digitorum communis (EDC) muscle was measured. TACS was applied at 10 and 20 Hz, respectively, for 10 min at 1 mA. Sham stimulation served as control condition. The data suggest that 10 Hz tACS significantly reduced low gamma band CMC during isometric contraction. This implies that tACS does not necessarily cause effects at stimulation frequency. Rather, the findings suggest cross-frequency interplay between alpha and low gamma band activity modulating functional interaction between motor cortex and muscle. PMID:24009573

  5. Are 1,5- and 1,7-dihydrodiimidazo[4,5-b:4‧,5‧-e]pyrazine the main products of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) alkaline hydrolysis? A DFT study of vibrational spectra

    NASA Astrophysics Data System (ADS)

    Kholod, Yana; Okovytyy, Sergiy; Kuramshina, Gulnara; Qasim, Mohammad; Gorb, Leonid; Furey, John; Honea, Patricia; Fredrickson, Herbert; Leszczynski, Jerzy

    2006-08-01

    The fully optimized geometries and force fields of the most stable conformation of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane and two tautomers 1,5- and 1,7-dihydrodiimidazo[4,5- b:4',5'- e]pyrazine were obtained at the B3LYP level of hybrid density functional theory with the 6-31G(d) basis set. The vibrational frequencies were calculated by scaling of force fields, and the vibrational spectra were interpreted taking into account potential energy distributions. DFT calculations provide good agreement between calculated and experimental vibrational frequencies, obtained for CL-20. The theoretical vibrational spectra of 1,5- and 1,7-dihydrodiimidazo[4,5- b:4',5'- e]pyrazine correspond to the experimental FTIR spectrum obtained for the CL-20 alkaline hydrolysis products.

  6. The 2.2 Hz oscillations in auroral electrons

    NASA Astrophysics Data System (ADS)

    Lepine, D. R.; Hall, D. S.; Bryant, D. A.; Johnstone, A. D.; Christiansen, P. J.; Gough, M. P.

    1980-06-01

    A Petrel rocket was launched from Kiruna on 25 January 1979 to compare electron intensities measured at auroral altitudes with related parameters measured at geostationary altitude by the satellite GEOS 2. A sequence of quasi-periodic oscillations in electron intensities were investigated, which appear to originate in the equatorial region, probably in the neighborhood of GEOS 2 was investigated. A similar frequency oscillation in the intensity of 500-Hz VLF emissions was observed at about the same time by the S300 wave experiment located on the satellite.

  7. Hearing thresholds of a harbor porpoise (Phocoena phocoena) for sweeps (1-2 kHz and 6-7 kHz bands) mimicking naval sonar signals.

    PubMed

    Kastelein, Ronald A; Hoek, Lean; de Jong, Christ A F

    2011-05-01

    The distance at which active naval sonar signals can be heard by harbor porpoises depends, among other factors, on the hearing thresholds of the species for those signals. Therefore the hearing sensitivity of a harbor porpoise was determined for 1 s up-sweep and down-sweep signals, mimicking mid-frequency and low-frequency active sonar sweeps (MFAS, 6-7 kHz band; LFAS, 1-2 kHz band). The 1-2 kHz sweeps were also tested with harmonics, as sonars sometimes produce these as byproducts of the fundamental signal. The hearing thresholds for up-sweeps and down-sweeps within each sweep pair were similar. The 50% detection threshold sound pressure levels (broadband, averaged over the signal duration) of the 1-2 kHz and 6-7 kHz sweeps were 75 and 67 dB re 1 μPa(2), respectively. Harmonic deformation of the 1-2 kHz sweeps reduced the threshold to 59 dB re 1 μPa(2). This study shows that the presence of harmonics in sonar signals can increase the detectability of a signal by harbor porpoises, and that tonal audiograms may not accurately predict the audibility of sweeps. LFAS systems, when designed to produce signals without harmonics, can operate at higher source levels than MFAS systems, at similar audibility distances for porpoises.

  8. Thomson Scattering at 250 kHz

    NASA Astrophysics Data System (ADS)

    Young, William; den Hartog, D. J.; Morton, L. A.; MST Team

    2015-11-01

    The fast Thomson scattering diagnostic on the MST Reversed-Field Pinch experiment now measures electron temperature at rates of up to 250 kHz, allowing for single shot analysis of phenomena that previously required ensembles of measurements from many shots. Recent laser upgrades include the addition of a second Nd:glass amplifier (giving a total of six amplifiers including four Nd:YAG stages) and optimization of neodymium doping levels within the glass amplifier stages to reduce thermal defocusing. The master-oscillator power-amplifier laser system operates in a pulse-burst mode where the laser generates multiple pulses per flashlamp firing and these bursts of laser pulses are repeated multiple times. When optimizing for the largest number of laser pulses, the laser produces up to 30 pulses at a rate of 100 kHz per burst repeated up to 4 times every 2 ms for a total of 120 temperature measurements per MST discharge. When optimizing for fastest pulsing rate, the laser can produce 8 pulses at 250 kHz within a single burst. A laser system upgrade currently underway is replacement of the diode-pumped pulsed Nd:YVO4 master oscillator with a CW laser chopped by an acoustic-optic modulator; this upgrade may enable pulsing rates faster than 250 kHz. This work is supported by the US DOE and NSF.

  9. Investigation on Two-Stage 300 HZ Pulse Tube Cryocooler

    NASA Astrophysics Data System (ADS)

    Cai, H. K.; Yang, L. W.; Hong, G. T.; Luo, E. C.; Zhou, Y.

    2010-04-01

    In the past few years, ultra-high frequency pulse tube cryocoolers are becoming a research hotspot for their portability and compactness in aerospace and aviation applications. For preliminary research, a two-stage pulse tube cryocooler working at 300 Hz driven by a thermoacoustic engine is established to investigate the problems due to ultra high frequency, and several results have been derived in our early reports. In order to study the effect of thermal penetration depth, this paper presents the cooler adopting copper mesh as the regenerator, and comparison with stainless steel mesh is given. In addition, the influence of inertance tube on the lowest possible cooler temperature is also tested. Finally, we discuss the improvement for getting a lower temperature.

  10. Benefits of 20 kHz PMAD in a nuclear space station

    NASA Astrophysics Data System (ADS)

    Sundberg, Gale R.

    Compared to existing systems, high frequency ac power provides higher efficiency, lower cost, and improved safety benefits. The 20 kHz power system has exceptional flexibility, is inherently user friendly, and is compatible with all types of energy sources; photovoltaic, solar dynamic, rotating machines and nuclear. A 25 kW, 20 kHz ac power distribution system testbed was recently (1986) developed. The testbed possesses maximum flexibility, versatility, and transparency to user technology while maintaining high efficiency, low mass, and reduced volume. Several aspects of the 20 kHz power management and distribution (PMAD) system that have particular benefits for a nuclear power Space Station are discussed.

  11. Benefits of 20 kHz PMAD in a nuclear space station

    NASA Technical Reports Server (NTRS)

    Sundberg, Gale R.

    1987-01-01

    Compared to existing systems, high frequency ac power provides higher efficiency, lower cost, and improved safety benefits. The 20 kHz power system has exceptional flexibility, is inherently user friendly, and is compatible with all types of energy sources; photovoltaic, solar dynamic, rotating machines and nuclear. A 25 kW, 20 kHz ac power distribution system testbed was recently (1986) developed. The testbed possesses maximum flexibility, versatility, and transparency to user technology while maintaining high efficiency, low mass, and reduced volume. Several aspects of the 20 kHz power management and distribution (PMAD) system that have particular benefits for a nuclear power Space Station are discussed.

  12. A reference-beam autocollimator with nanoradian sensitivity from mHz to kHz and dynamic range of 107

    NASA Astrophysics Data System (ADS)

    Arp, T. B.; Hagedorn, C. A.; Schlamminger, S.; Gundlach, J. H.

    2013-09-01

    We describe an autocollimating optical angle sensor with a dynamic range of 9 mrad and nrad/sqrt{textrm {Hz}} sensitivity at frequencies from 5 mHz to 3 kHz. This work improves the standard multi-slit autocollimator design by adding two optical components, a reference mirror and a condensing lens. This autocollimator makes a differential measurement between a reference mirror and a target mirror, suppressing common-mode noise sources. The condensing lens reduces optical aberrations, increases intensity, and improves image quality. To further improve the stability of the device at low frequencies the body of the autocollimator is designed to reduce temperature variations and their effects. A new data processing technique was developed in order to suppress the effects of imperfections in the CCD.

  13. A reference-beam autocollimator with nanoradian sensitivity from mHz to kHz and dynamic range of 10(7).

    PubMed

    Arp, T B; Hagedorn, C A; Schlamminger, S; Gundlach, J H

    2013-09-01

    We describe an autocollimating optical angle sensor with a dynamic range of 9 mrad and nrad/√Hz sensitivity at frequencies from 5 mHz to 3 kHz. This work improves the standard multi-slit autocollimator design by adding two optical components, a reference mirror and a condensing lens. This autocollimator makes a differential measurement between a reference mirror and a target mirror, suppressing common-mode noise sources. The condensing lens reduces optical aberrations, increases intensity, and improves image quality. To further improve the stability of the device at low frequencies the body of the autocollimator is designed to reduce temperature variations and their effects. A new data processing technique was developed in order to suppress the effects of imperfections in the CCD.

  14. Environmental and Pharmacological Modulation of Amphetamine-Induced 50-kHz Ultrasonic Vocalizations in Rats

    PubMed Central

    Rippberger, Henrike; van Gaalen, Marcel M.; Schwarting, Rainer K.W.; WÖhr, Markus

    2015-01-01

    Rats emit high-frequency 50-kHz ultrasonic vocalizations (USV) in appetitive situations like social interactions. Drugs of abuse are probably the most potent non-social elicitors of 50-kHz USV, possibly reflecting their euphorigenic properties. Psychostimulants induce the strongest elevation in 50-kHz USV emission, particularly amphetamine (AMPH), either when applied systemically or locally into the nucleus accumbens (Nacc). Emission of AMPH-induced 50-kHz USV depends on test context, such as the presence of conspecifics, and can be manipulated pharmacologically by targeting major neurotransmitter systems, including dopamine (DA), noradrenaline (NA), and serotonin (5-HT), but also protein kinase C (PKC) signaling. Several D1 and D2 receptor antagonists, as well as typical and atypical antipsychotics block the AMPH-induced elevation in 50-kHz USV. Inhibiting D1 and D2 receptors in the Nacc abolishes AMPH-induced 50-kHz USV, indicating a key role for this brain area. NA neurotransmission also regulates AMPH-induced 50-kHz USV emission given that α1 receptor antagonists and α2 receptor agonists exert attenuating effects. Supporting the involvement of the 5-HT system, AMPH-induced 50-kHz USV are attenuated by 5-HT2C receptor activation, whereas 5-HT2C receptor antagonism leads to the opposite effect. Finally, treatment with lithium, tamoxifen, and myricitrin was all found to result in a complete abolishment of the AMPH-induced increase in 50-kHz USV, suggesting the involvement of PKC signaling. Neurotransmitter systems involved in AMPH-induced 50-kHz USV emission only partially overlap with other AMPH-induced behaviors like hyperlocomotion. The validity of AMPH-induced 50-kHz USV as a preclinical model for neuropsychiatric disorders is discussed, particularly with relevance to altered drive and mood seen in bipolar disorder. PMID:26411764

  15. Spectroscopic observations of HZ Herculis. II

    NASA Technical Reports Server (NTRS)

    Bopp, B. W.; Grupsmith, G.; Mcmillan, R. S.; Vanden Bout, P. A.; Wootten, H. A.

    1973-01-01

    Preliminary results from an extensive series of spectroscopic observations of the HZ Her optical counterpart of the eclipsing, pulsating X-ray binary Her X-1. Spectrograms with a dispersion of 30 A/mm reveal a spectral type as late as F5 near minimum in the light curve with the G-band and metallic lines present. Narrow Fe lines show that HZ Her is not a rapid rotator. Low-dispersion (115 A/mm) spectra, obtained with 10-minute time resolution, reveal rapid (10-min) variations in the 4640 N III emission and in the 4471 He I absorbtion features. The H-beta absorption is variable in equivalent width, and shows evidence of being partially filled with emission.

  16. Improvements in GPS precision: 10 Hz to one day

    NASA Astrophysics Data System (ADS)

    Choi, Kyuhong

    Ashtech MicroZ and ZFX as well as Trimble NetRS receivers. The Trimble NetRS receiver noise has a timeseries standard deviation double that of Ashtech MicroZ receivers. Also, the power spectral density function has a 0.1 Hz peak. Noise power shows white noise for the frequency range from 2 Hz and higher. Each research project assesses the methods to reduce the noises and/or biases in various time intervals. Each method considered in this dissertation will fulfill the needs for scientific applications.

  17. Plasma antennas driven by 5–20 kHz AC power supply

    SciTech Connect

    Zhao, Jiansen Chen, Yuli; Sun, Yang; Wu, Huafeng; Liu, Yue; Yuan, Qiumeng

    2015-12-15

    The experiments described in this work were performed with the aim of introducing a new plasma antenna that was excited by a 5–20 kHz alternating current (AC) power supply, where the antenna was transformed into a U-shape. The results show that the impedance, voltage standing-wave ratio (VSWR), radiation pattern and gain characteristics of the antenna can be controlled rapidly by varying not only the discharge power, but also by varying the discharge frequency in the range from 5 to 20 kHz. When the discharge frequency is adjusted from 10 to 12 kHz, the gain is higher within a relatively broad frequency band and the switch-on time is less than 1 ms when the discharge power is less than 5 W, meaning that the plasma antenna can be turned on and off rapidly.

  18. Synoptic Analysis of the GUFMEX Return-Flow Event of 10-12 March 1988.

    NASA Astrophysics Data System (ADS)

    Merrill, Robert T.

    1992-08-01

    Return flow is the moist southerly wind that develops over the Gulf of Mexico after an outbreak of polar air. Surface, aircraft, and special rawinsonde data collected during the Gulf of Mexico Experiment (GUFMEX) are used to describe the return-flow event of 10-12 March 1988. The return flow at the surface contained both modified polar air and prefrontal air. The surface moist layer was capped by a stable subsident layer except over its western extremity, where an elevated mixed layer was observed. At later stages, a moist layer aloft was present as well.These complex airmass structures arose because both advective and diabatic processes are significant in a return flow. The roles of each are inferred qualitatively by comparing the observed mixing-ratio distribution to the equilibrium conditions expected for the observed sea surface temperatures. The surface moisture distribution can be explained by rapid modification of offshore flow to near equilibrium, followed by onshore (return) flow of the modified air with little additional change. The structure above the surface moist layer is explained by differential advection that juxtaposed three different airstreams. Though no significant severe weather followed this particular case, the processes that typically lead to a favorable severe-weather environment are evident.

  19. 41Ca ultratrace determination with isotopic selectivity > 10(12) by diode-laser-based RIMS.

    PubMed

    Müller, P; Bushaw, B A; Blaum, K; Diel, S; Geppert, C; Nähler, A; Trautmann, N; Nörtershäuser, W; Wendt, K

    2001-07-01

    41Ca ultratrace determination by diode-laser-based resonance ionization mass spectrometry with extremely high isotopic selectivity is presented. Application to environmental dosimetry of nuclear reactor components, to cosmochemical investigations of production cross sections, and biomedical isotope-tracer studies of human calcium kinetics are discussed. Future investigations are possible use in 41Ca-radiodating. Depending on the application, 41Ca isotopic abundances in the range of 10(-9) to 10(-15) relative to the dominant stable isotope 40Ca must be determined. Either double- or triple-resonance optical excitation with narrow-band extended cavity diode lasers and subsequent non-resonant photoionization of calcium in a collimated atomic beam were used. The resulting photoions are detected with a quadrupole mass spectrometer optimized for background reduction and neighboring mass suppression. Applying the full triple-resonance scheme provides a selectivity of approximately 5 x 10(12) in the suppression of neighboring isotopes and > 10(8) for isobars, together with an overall detection efficiency of approximately 5 x 10(-5). Measurements on a variety of sample types are discussed; the accuracy and reproducibility of the resulting 41Ca/40Ca isotope ratios was better than 5%.

  20. Threshold received sound pressure levels of single 1-2 kHz and 6-7 kHz up-sweeps and down-sweeps causing startle responses in a harbor porpoise (Phocoena phocoena).

    PubMed

    Kastelein, Ronald A; Steen, Nele; Gransier, Robin; Wensveen, Paul J; de Jong, Christ A F

    2012-03-01

    Mid-frequency and low-frequency sonar systems produce frequency-modulated sweeps which may affect harbor porpoises. To study the effect of sweeps on behavioral responses (specifically "startle" responses, which we define as sudden changes in swimming speed and/or direction), a harbor porpoise in a large pool was exposed to three pairs of sweeps: a 1-2 kHz up-sweep was compared with a 2-1 kHz down-sweep, both with and without harmonics, and a 6-7 kHz up-sweep was compared with a 7-6 kHz down-sweep without harmonics. Sweeps were presented at five spatially averaged received levels (mRLs; 6 dB steps; identical for the up-sweep and down-sweep of each pair). During sweep presentation, startle responses were recorded. There was no difference in the mRLs causing startle responses for up-sweeps and down-sweeps within frequency pairs. For 1-2 kHz sweeps without harmonics, a 50% startle response rate occurred at mRLs of 133 dB re 1 μPa; for 1-2 kHz sweeps with strong harmonics at 99 dB re 1 μPa; for 6-7 kHz sweeps without harmonics at 101 dB re 1 μPa. Low-frequency (1-2 kHz) active naval sonar systems without harmonics can therefore operate at higher source levels than mid-frequency (6-7 kHz) active sonar systems without harmonics, with similar startle effects on porpoises.

  1. New architecture of tunable mechanical monolithic horizontal sensor for low frequency seismic noise measurement

    NASA Astrophysics Data System (ADS)

    Acernese, Fausto; Giordano, Gerardo; De Rosa, Rosario; Romano, Rocco; Vilasi, Silvia; Barone, Fabrizio

    2010-10-01

    This paper describes a new mechanical architecture of the monolithic tunable folded pendulum, developed at the University of Salerno, configurable both as seismometer and, in a force-feedback configuration, as accelerometer. Typical applications are the remote monitoring of seismic and newtonian noises for geophysical applications. This sensor, shaped with precision machining and electric-discharge-machining, like the previous versions, is a very compact instrument, very sensitive in the low-frequency seismic noise band, with a very good immunity to environmental noises. Important characteristics are the large band (10-6 - 10mHz), the tunability of the resonance frequency and the laser optical readout, that integrates an optical lever and a laser interferometer. The theoretical sensitivity curves, largely improved due to a new design of the pendulum arms and of the electronics, are in a very good agreement with the measurements. In particular, a very good sensitivity (10-12 m/Hz1/2) has been obtained in the band 0.1 - 10 Hz). Prototypes of monolithic seismometers are already operational in selected sites around the world both to remotely acquire data for scientific analysis of seismic noise and to collect all the useful information to understand their performances in the very low frequency band. The results of the monolithic sensor as accelerometer (force feed-back configuration) are also presented and discussed.

  2. SOFT LAGS IN NEUTRON STAR kHz QUASI-PERIODIC OSCILLATIONS: EVIDENCE FOR REVERBERATION?

    SciTech Connect

    Barret, Didier

    2013-06-10

    High frequency soft reverberation lags have now been detected from stellar mass and supermassive black holes. Their interpretation involves reflection of a hard source of photons onto an accretion disk, producing a delayed reflected emission, with a time lag consistent with the light travel time between the irradiating source and the disk. Independently of the location of the clock, the kHz quasi-periodic oscillation (QPO) emission is thought to arise from the neutron star boundary layer. Here, we search for the signature of reverberation of the kHz QPO emission, by measuring the soft lags and the lag energy spectrum of the lower kHz QPOs from 4U1608-522. Soft lags, ranging from {approx}15 to {approx}40 {mu}s, between the 3-8 keV and 8-30 keV modulated emissions are detected between 565 and 890 Hz. The soft lags are not constant with frequency and show a smooth decrease between 680 Hz and 890 Hz. The broad band X-ray spectrum is modeled as the sum of a disk and a thermal Comptonized component, plus a broad iron line, expected from reflection. The spectral parameters follow a smooth relationship with the QPO frequency, in particular the fitted inner disk radius decreases steadily with frequency. Both the bump around the iron line in the lag energy spectrum and the consistency between the lag changes and the inferred changes of the inner disk radius, from either spectral fitting or the QPO frequency, suggest that the soft lags may indeed involve reverberation of the hard pulsating QPO source on the disk.

  3. Coherent neocortical 40-Hz oscillations are not present during REM sleep.

    PubMed

    Castro, Santiago; Falconi, Atilio; Chase, Michael H; Torterolo, Pablo

    2013-04-01

    During cognitive processes there are extensive interactions between various regions of the cerebral cortex. Oscillations in the gamma frequency band (≈40 Hz) of the electroencephalogram (EEG) are involved in the binding of spatially separated but temporally correlated neural events, which results in a unified perceptual experience. The extent of these interactions can be examined by means of a mathematical algorithm called 'coherence', which reflects the 'strength' of functional interactions between cortical areas. The present study was conducted to analyse EEG coherence in the gamma frequency band of the cat during alert wakefulness (AW), quiet wakefulness (QW), non-rapid eye movement (NREM) sleep and rapid eye movement (REM) sleep. Cats were implanted with electrodes in the frontal, parietal and occipital cortices to monitor EEG activity. Coherence values within the gamma frequency (30-100 Hz) from pairs of EEG recordings were analysed. A large increase in coherence occurred between all cortical regions in the 30-45 Hz frequency band during AW compared with the other behavioral states. As the animal transitioned from AW to QW and from QW to NREM sleep, coherence decreased to a moderate level. Remarkably, there was practically no EEG coherence in the entire gamma band spectrum (30-100 Hz) during REM sleep. We conclude that functional interactions between cortical areas are radically different during sleep compared with wakefulness. The virtual absence of gamma frequency coherence during REM sleep may underlie the unique cognitive processing that occurs during dreams, which is principally a REM sleep-related phenomenon. PMID:23406153

  4. The effects of probe-tone frequency on the acoustic-reflex growth function.

    PubMed

    Lutolf, John J; O'Malley, Honor; Silman, Shlomo

    2003-01-01

    Acoustic-reflex growth functions (ARGFs) were obtained from 20 normal-hearing listeners. Contralateral acoustic reflexes (ARs) were elicited with pure tones of 2000 Hz. The magnitude of changes in static compliant susceptance (BA) and conductance (GA) were monitored with probe-tone frequencies of 226 Hz, 678 Hz and 1000 Hz. ARGFs were obtained with six combinations of probe-tone frequency/admittance component: 226 Hz BA, 226 Hz GA, 678 Hz BA, 678 Hz GA, 1000 Hz BA, and 1000 Hz GA. Peak conductance (GA) and susceptance (BA) ARs were largest within the 678 Hz GA and 1000 Hz BAARGFs, respectively. Among high-frequency probe tones, the patterns of AR growth were larger and less variable for the 678 Hz GA ARGF and the 1000 Hz BA ARGF as determined by the magnitude of their linear (b1) and quadratic (b2) polynomial coefficients and the value of their squared correlation coefficients (R2).

  5. Real-Time Determination of Absolute Frequency in Continuous-Wave Terahertz Radiation with a Photocarrier Terahertz Frequency Comb Induced by an Unstabilized Femtosecond Laser

    NASA Astrophysics Data System (ADS)

    Minamikawa, Takeo; Hayashi, Kenta; Mizuguchi, Tatsuya; Hsieh, Yi-Da; Abdelsalam, Dahi Ghareab; Mizutani, Yasuhiro; Yamamoto, Hirotsugu; Iwata, Tetsuo; Yasui, Takeshi

    2016-05-01

    A practical method for the absolute frequency measurement of continuous-wave terahertz (CW-THz) radiation uses a photocarrier terahertz frequency comb (PC-THz comb) because of its ability to realize real-time, precise measurement without the need for cryogenic cooling. However, the requirement for precise stabilization of the repetition frequency ( f rep) and/or use of dual femtosecond lasers hinders its practical use. In this article, based on the fact that an equal interval between PC-THz comb modes is always maintained regardless of the fluctuation in f rep, the PC-THz comb induced by an unstabilized laser was used to determine the absolute frequency f THz of CW-THz radiation. Using an f rep-free-running PC-THz comb, the f THz of the frequency-fixed or frequency-fluctuated active frequency multiplier chain CW-THz source was determined at a measurement rate of 10 Hz with a relative accuracy of 8.2 × 10-13 and a relative precision of 8.8 × 10-12 to a rubidium frequency standard. Furthermore, f THz was correctly determined even when fluctuating over a range of 20 GHz. The proposed method enables the use of any commercial femtosecond laser for the absolute frequency measurement of CW-THz radiation.

  6. Influence of 60-Hz magnetic fields on sea urchin development

    SciTech Connect

    Zimmerman, S.; Zimmerman, A.M.; Winters, W.D.; Cameron, I.L. )

    1990-01-01

    Continuous exposure of sea urchin (Strongylocentrotus purpuratus) embryos at 18 degrees C to a cyclic 60-Hz magnetic field at 0.1 mT rms beginning 4 min after insemination caused a significant developmental delay during the subsequent 23 hours. No delay in development was recorded for periods up to 18 hours after fertilization. At 18 h, most embryos were in the mesenchyme blastula stage. At 23 h, most control embryos were in mid-gastrula whereas most magnetic-field-exposed embryos were in the early gastrula stage. Thus an estimated 1-h delay occurred between these developmental stages. The results are discussed in terms of possible magnetic-field modification of transcription as well as interference with cell migration during gastrulation. The present study extends and supports the growing body of information about potential effects of exposures to extremely-low-frequency (ELF) magnetic fields on developing organisms.

  7. EV drivetrain inverter with V/HZ optimization

    DOEpatents

    Gritter, David J.; O'Neil, Walter K.

    1986-01-01

    An inverter (34) which provides power to an A.C. machine (28) is controlled by a circuit (36) employing PWM control strategy whereby A.C. power is supplied to the machine at a preselectable frequency and preselectable voltage. This is accomplished by the technique of waveform notching in which the shapes of the notches are varied to determine the average energy content of the overall waveform. Through this arrangement, the operational efficiency of the A.C. machine is optimized. The control circuit includes a micro-computer which calculates optimized machine control data signals from various parametric inputs and during steady state load conditions, seeks a best V/HZ ratio to minimize battery current drawn (system losses) from a D.C. power source (32). In the preferred embodiment, the present invention is incorporated within an electric vehicle (10) employing a 144 VDC battery pack and a three-phase induction motor (18).

  8. 20 kHz Space Station power system

    NASA Technical Reports Server (NTRS)

    Hansen, Irving G.; Wolff, Fredrick J.

    1986-01-01

    The Space Station represents the next major U.S. commitment in space. The efficient delivery of power to multiple user loads is key to that success. In 1969, NASA Lewis Research Center began a series of studies with component and circuit developments that led to the high frequency bi-directional, four quadrant resonant driven converter. Additional studies and subsequent developments into the early 1980's have shown how the high frequency ac power system could provide overall advantages to many aerospace power systems. Because of its wide versatility, it also has outstanding advantages for the Space Station Program and its wide range of users. High frequency ac power provides higher efficiency, lower cost, and improved safety. The 20 kHz power system has exceptional flexibility, is inherently user friendly, and is compatible with all types of energy sources - photovoltaic, solar dynamic, rotating machines or nuclear Lewis distribution system testbed. The testbed demonstrates flexibility, versatility, and transparency to user technology as well as high efficiency, low mass, and reduced volume.

  9. Low potency and limited efficacy of antiepileptic drugs in the mouse 6 Hz corneal kindling model.

    PubMed

    Leclercq, K; Matagne, A; Kaminski, R M

    2014-05-01

    Corneal kindling is a useful alternative to electrically induced amygdala or hippocampal kindling, which requires advanced surgical and EEG techniques that may not be easily available in many laboratories. Therefore the first aim of this study was to evaluate whether repeated 6 Hz corneal stimulation in mice would lead to an increased and persistent seizure response as described for higher frequency (50/60 Hz) corneal kindling. Male NMRI mice stimulated twice daily (except weekends) for 3 s with 6 Hz electrical current at 44 mA displayed robust kindling development, i.e., a progressive increase in seizure severity. The majority of the animals (about 90%) developed a fully kindled state, defined as at least 10 consecutive stage 3-5 seizures within 5 weeks of corneal stimulation. Afterwards, the fully kindled state was maintained for at least 8 weeks with only two days of stimulations per week. Next, the protective efficacy of four mechanistically different antiepileptic drugs (AEDs; clonazepam, valproate, carbamazepine and levetiracetam) was assessed and compared between 6 Hz and 50 Hz fully kindled mice. All tested AEDs showed a relatively lower potency in the 6 Hz kindling model and a limited efficacy against partial seizures was observed with carbamazepine and levetiracetam. We can conclude that 6 Hz kindling may be more advantageous than the previously described 50/60 Hz corneal kindling models due to its robustness and persistence of the fully kindled state. Furthermore, the observed low potency and limited efficacy of AEDs in 6 Hz fully kindled mice suggest that this model could be a useful tool in the discovery of novel AEDs targeting treatment resistant epilepsy.

  10. Long-term underwater sound measurements in the shipping noise indicator bands 63Hz and 125Hz from the port of Falmouth Bay, UK.

    PubMed

    Garrett, J K; Blondel, Ph; Godley, B J; Pikesley, S K; Witt, M J; Johanning, L

    2016-09-15

    Chronic low-frequency anthropogenic sound, such as shipping noise, may be negatively affecting marine life. The EU's Marine Strategy Framework Directive (MSFD) includes a specific indicator focused on this noise. This indicator is the yearly average sound level in third-octave bands with centre frequencies at 63Hz and 125Hz. These levels are described for Falmouth Bay, UK, an active port at the entrance to the English Channel. Underwater sound was recorded for 30min h(-1) over the period June 2012 to November 2013 for a total of 435days. Mean third-octave levels were louder in the 125-Hz band (annual mean level of 96.0dB re 1μPa) than in the 63-Hz band (92.6dB re 1 μPa). These levels and variations are assessed as a function of seasons, shipping activity and wave height, providing comparison points for future monitoring activities, including the MSFD and emerging international regulation.

  11. Long-term underwater sound measurements in the shipping noise indicator bands 63Hz and 125Hz from the port of Falmouth Bay, UK.

    PubMed

    Garrett, J K; Blondel, Ph; Godley, B J; Pikesley, S K; Witt, M J; Johanning, L

    2016-09-15

    Chronic low-frequency anthropogenic sound, such as shipping noise, may be negatively affecting marine life. The EU's Marine Strategy Framework Directive (MSFD) includes a specific indicator focused on this noise. This indicator is the yearly average sound level in third-octave bands with centre frequencies at 63Hz and 125Hz. These levels are described for Falmouth Bay, UK, an active port at the entrance to the English Channel. Underwater sound was recorded for 30min h(-1) over the period June 2012 to November 2013 for a total of 435days. Mean third-octave levels were louder in the 125-Hz band (annual mean level of 96.0dB re 1μPa) than in the 63-Hz band (92.6dB re 1 μPa). These levels and variations are assessed as a function of seasons, shipping activity and wave height, providing comparison points for future monitoring activities, including the MSFD and emerging international regulation. PMID:27393210

  12. Broadband frequency demodulator for detecting small frequency shifts

    NASA Astrophysics Data System (ADS)

    Weyand, K.; Simon, E.

    1980-03-01

    A technique is presented that enables the indication of the smallest frequency-modulation shifts over a wide carrier-frequency range. Through coil-less modulation following conversion of the carrier-frequency, and subsequent phase-sensitive rectification of the low-frequency signal, it is possible to achieve high linearity and resolution over a frequency range of 20 kHz through 4 MHz. It is noted that the smallest frequency shift that can still be detected is 10 to the -4th Hz.

  13. Laser frequency stabilization for LISA

    NASA Technical Reports Server (NTRS)

    Mueller, Guido; McNamara, Paul; Thorpe, Ira; Camp, Jordan

    2005-01-01

    The requirement on laser frequency noise in the Laser Interferometer Space Antenna (LISA) depends on the velocity and our knowledge of the position of each spacecraft of the interferometer. Currently it is assumed that the lasers must have a pre-stabilized frequency stability of 30Hz/square root of Hz over LISA'S most sensitive frequency band (3 mHz - 30 mHz). The intrinsic frequency stability of even the most stable com- mercial lasers is several orders of magnitude above this level. Therefore it is necessary to stabilize the laser frequency to an ultra-stable frequency reference which meets the LISA requirements. The baseline frequency reference for the LISA lasers are high finesse optical cavities based on ULE spacers. We measured the stability of two ULE spacer cavities with respect to each other. Our current best results show a noise floor at, or below, 30 Hz/square root of Hz above 3 mHz. In this report we describe the experimental layout of the entire experiment and discuss the limiting noise sources.

  14. 40 Hz auditory steady state response to linguistic features of stimuli during auditory hallucinations.

    PubMed

    Ying, Jun; Yan, Zheng; Gao, Xiao-rong

    2013-10-01

    The auditory steady state response (ASSR) may reflect activity from different regions of the brain, depending on the modulation frequency used. In general, responses induced by low rates (≤40 Hz) emanate mostly from central structures of the brain, and responses from high rates (≥80 Hz) emanate mostly from the peripheral auditory nerve or brainstem structures. Besides, it was reported that the gamma band ASSR (30-90 Hz) played an important role in working memory, speech understanding and recognition. This paper investigated the 40 Hz ASSR evoked by modulated speech and reversed speech. The speech was Chinese phrase voice, and the noise-like reversed speech was obtained by temporally reversing the speech. Both auditory stimuli were modulated with a frequency of 40 Hz. Ten healthy subjects and 5 patients with hallucination symptom participated in the experiment. Results showed reduction in left auditory cortex response when healthy subjects listened to the reversed speech compared with the speech. In contrast, when the patients who experienced auditory hallucinations listened to the reversed speech, the auditory cortex of left hemispheric responded more actively. The ASSR results were consistent with the behavior results of patients. Therefore, the gamma band ASSR is expected to be helpful for rapid and objective diagnosis of hallucination in clinic. PMID:24142731

  15. Thomson scattering at 250 kHz

    NASA Astrophysics Data System (ADS)

    Young, W. C.; Den Hartog, D. J.

    2015-12-01

    Several upgrades have been applied to the high-repetition-rate Thomson scattering diagnostic on the MST experiment, having increased the rate and number of electron temperature measurements. The detector portion of the Thomson scattering system requires 1.5-2.0 J, 10-20 ns laser pulses at 1064 nm. A high-repetition-rate laser produces suitable pulses for short 3-4 pulse bursts with only 3 μs pulse spacing. Alternatively, the laser timing can be optimized to maximize the number of pulses in a single burst, producing up to 44 pulses at a rate of 100 kHz. The laser follows a master oscillator, power amplifier architecture. Upgrades to the laser include: a new acousto-optic modulator chopped CW laser based master oscillator, a sixth power amplifier, optimized Nd doping within Nd:glass amplifiers via optical modeling of the pump chamber, and a yet to be installed new cavity reflector. Additionally, a new long wavelength filter has been added to the Thomson scattering diagnostic's polychromator based detector, allowing possible detection of net electron drift.

  16. Evidence for a High-Pressure Phase Transition of ε-2,4,6,8,10,12-hexanitrohexaazaisowurtzitane (CL-20) Using Vibrational Spectroscopy

    SciTech Connect

    Ciezak, J.; Jenkins, T; Liu, Z

    2007-01-01

    The high-pressure response of {epsilon}-2,4,6,8,10,12-hexanitrohexaazaisowurtizane (CL-20) has been examined to 27 GPa in diamond anvil cells using vibrational spectroscopy. The results reveal evidence of an {epsilon}{yields}{Upsilon} pressure-induced phase transition between 4.1 and 6.4 GPa and suggest the existence of a {Upsilon}{yields}{zeta} transition near 18.7 GPa. Several Raman and infrared frequencies were found to decrease in intensity as the phase boundaries are approached. An anomalous intensity increase was noted in the C-N-C infrared mode that is believed to result from an increase in the Raman cross-section due to a stronger interlayer coupling under pressure.

  17. Strand V: Education for Survival. First Aid and Survival Education. Health Curriculum Materials Grades 10-12.

    ERIC Educational Resources Information Center

    New York State Education Dept., Albany. Bureau of Secondary Curriculum Development.

    GRADES OR AGES: Grades 10-12. SUBJECT MATTER: First aid and survival education. ORGANIZATION AND PHYSICAL APPEARANCE: The guide is divided into six sections: transportation of the injured, automobile accidents, conditions resulting from nuclear explosion, chemical warfare, natural catastrophes, and psychological first aid. The publication format…

  18. Dynamics of Clothing II. Curriculum Guide. A Family and Consumer Sciences Education Course of Study for Grades 10-12.

    ERIC Educational Resources Information Center

    Hunger, Dean-Ellen, Ed.; Hancey, Helen-Louise; Hendrickson, Diane; Hicks, Camille; Munns, Barbara; Price, Barbara

    This document is a nine-unit curriculum guide for a high school (grades 10-12) course in clothing instruction. The units contain one or two lessons on the following topics: (1) psychological aspects of clothing (behavior, image, and dress; self-concept and self-image); (2) wardrobe selections (wardrobe consumerism, wardrobe evaluation and…

  19. Validity and interunit reliability of 10 Hz and 15 Hz GPS units for assessing athlete movement demands.

    PubMed

    Johnston, Richard J; Watsford, Mark L; Kelly, Stephen J; Pine, Matthew J; Spurrs, Robert W

    2014-06-01

    The purpose of this study was to assess the validity and interunit reliability of 10 Hz (Catapult) and 15 Hz (GPSports) Global Positioning System (GPS) units and investigate the differences between these units as measures of team sport athlete movement demands. A team sport simulation circuit was completed by 8 trained male participants. The movement demands examined included: total distance covered (TD), average peak speed, and the distance covered, time spent, and the number of efforts performed low-speed running (0.00-13.99 km · h(-1)), high-speed running (14.00-19.99 km · h(-1)), and very high-speed running (>20.00 km · h(-1)). The degree of difference between the 10 Hz and the 15 Hz GPS units and validity was assessed using a paired samples t-test. Pearson's correlations were also used for validity assessment. Interunit reliability was established using percentage typical error of measurement (%TEM) and intraclass correlations. The findings revealed that 10 Hz GPS units were a valid (p > 0.05) and reliable (%TEM = 1.3%) measure of TD. In contrast, the 15 Hz GPS units exhibited lower validity for TD and average peak speed. Further, as the speed of movement increased the level of error for the 10 Hz and 15 Hz GPS units increased (%TEM = 0.8-19.9). The findings from this study suggest that comparisons should not be undertaken between 10 Hz and 15 Hz GPS units. In general, the 10 Hz GPS units measured movement demands with greater validity and interunit reliability than the 15 Hz units, however, both 10 Hz and 15 Hz units provided the improved measures of movement demands in comparison to 1 Hz and 5 Hz GPS units.

  20. Radar Symposium, 7th, Universitaet Ulm, Federal Republic of Germany, Oct. 10-12, 1989, Reports

    NASA Astrophysics Data System (ADS)

    Baur, K.

    Various papers on radar are presented. Individual topics addressed include: aspects of long-wave radiation, future NATO identification systems, experimental X-band SAR, results of first tests of the ROSAR method, concept and results of the azimuth Quick-Look Processor for the SAR aircraft, specification of an inertial navigation system for experimental SAR, detection of slowly moving targets with airborne radar, fast method for disturbance-free two-dimensional ISAR imaging, development and optimization of a coastal radar system, determination of orientation accuracy in curving trajectories, radome structures for high-frequency applications. Also discussed are: monolithically integrated GaAs switching circuits for the millimeter wave range, new pulse compression methods for periodically phase-coded signal transmission, architectures of programmable radar signal processors, evaluation of the period length of periodic signals, interactive simulation system for multisensor systems, intelligent radar data processing, knowledge-based components of a tracking system, radar signatures of highly resolving millimeter wave sensors.

  1. 47 CFR 80.209 - Transmitter frequency tolerances.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    .... 2 For transmitters with digital selective calling emissions 10 Hz. 2 For all other emissions 50 Hz... craft stations: 50 Hz. (4) Band 72-76 MHz: (i) Fixed stations: Operating in the 72.0-73.0 and 75.4-76.0... shown in the following table. Tolerances are given as parts in 106 unless shown in Hz. Frequency...

  2. High-frequency and high-quality silicon carbide optomechanical microresonators.

    PubMed

    Lu, Xiyuan; Lee, Jonathan Y; Lin, Qiang

    2015-01-01

    Silicon carbide (SiC) exhibits excellent material properties attractive for broad applications. We demonstrate the first SiC optomechanical microresonators that integrate high mechanical frequency, high mechanical quality, and high optical quality into a single device. The radial-breathing mechanical mode has a mechanical frequency up to 1.69 GHz with a mechanical Q around 5500 in atmosphere, which corresponds to a fm · Qm product as high as 9.47 × 10(12) Hz. The strong optomechanical coupling allows us to efficiently excite and probe the coherent mechanical oscillation by optical waves. The demonstrated devices, in combination with the superior thermal property, chemical inertness, and defect characteristics of SiC, show great potential for applications in metrology, sensing, and quantum photonics, particularly in harsh environments that are challenging for other device platforms. PMID:26585637

  3. A kHz heat-load shutter for white-beam experiments at synchrotron sources.

    PubMed

    Gembicky, Milan; Adachi, Shin Ichi; Coppens, Philip

    2007-05-01

    A heat-load shutter capable of frequencies from one to several tens of kHz and window times from 10 micros up to 1 ms is described. In the current configuration the water-cooled shutter absorbs approximately 99% of the heat generated by the white beam. It has been successfully used for extended periods synchronized with a Jülich pulse-selector operating at 946 Hz. The temperature of the pulse-selector remained constant during a three-day continuous operation. Flexibility is provided by the interchangeability of the chopper disc.

  4. Monitoring audiometry for occupational hearing loss: A case for eliminating 500 Hz

    NASA Astrophysics Data System (ADS)

    Stephenson, Mark

    2003-04-01

    Audiometric monitoring is an important element in hearing conservation programs. Nearly every existing hearing conservation standard dictate that hearing thresholds should be measured at specific frequencies, and that 500 Hz be among those frequencies tested. Actual and estimated noise-induced permanent threshold shifts were evaluated as a function of exposure duration and exposure level. The results demonstrate 500 Hz to be of little value in assessing noise-induced hearing loss for typical industrial noise exposures of up to 40 years, at least for time-weighted average exposures of up to 100 dBA. Furthermore, few hearing conservation programs currently require audiometric monitoring to be performed in an environment that meets ANSI standards for maximum permissible background noise levels. This is particularly likely to compromise hearing testing at 500 Hz. As a result, this paper argues against the need for testing at 500 Hz, and recommends it be eliminated as a required test frequency in audiometric monitoring for noise-induced occupational hearing loss.

  5. Adsorption of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) on a soil organic matter. A DFT M05 computational study.

    PubMed

    Sviatenko, Liudmyla K; Gorb, Leonid; Shukla, Manoj K; Seiter, Jennifer M; Leszczynska, Danuta; Leszczynski, Jerzy

    2016-04-01

    Adsorption of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) by soil organic matter considering the Leonardite Humic Acid (LHA) model at the M05/tzvp level of Density Functional Theory (DFT) applying cluster approximation has been investigated. Different orientations of CL-20 toward LHA surface were examined. It was found that deprotonation of LHA is required to obtain stable complexes with CL-20. Hydrogen bonds between CL-20 and deprotonated LHA were analyzed applying the atoms in molecules (AIM) theory. An attachment or removal of an electron with respect to the complex does not have significant effect on mutual orientation of the adsorbent in complexes. It was shown that adsorbed CL-20 does not undergo redox transformation and, therefore, adsorption on soil organic matter may be responsible for decrease of the degradation rate of CL-20 in soil.

  6. Adsorption of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) on a soil organic matter. A DFT M05 computational study.

    PubMed

    Sviatenko, Liudmyla K; Gorb, Leonid; Shukla, Manoj K; Seiter, Jennifer M; Leszczynska, Danuta; Leszczynski, Jerzy

    2016-04-01

    Adsorption of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) by soil organic matter considering the Leonardite Humic Acid (LHA) model at the M05/tzvp level of Density Functional Theory (DFT) applying cluster approximation has been investigated. Different orientations of CL-20 toward LHA surface were examined. It was found that deprotonation of LHA is required to obtain stable complexes with CL-20. Hydrogen bonds between CL-20 and deprotonated LHA were analyzed applying the atoms in molecules (AIM) theory. An attachment or removal of an electron with respect to the complex does not have significant effect on mutual orientation of the adsorbent in complexes. It was shown that adsorbed CL-20 does not undergo redox transformation and, therefore, adsorption on soil organic matter may be responsible for decrease of the degradation rate of CL-20 in soil. PMID:26814703

  7. Statistical analysis of Stromboli VLP tremor in the band [0.1-0.5] Hz: some consequences for vibrating structures

    NASA Astrophysics Data System (ADS)

    de Lauro, E.; de Martino, S.; Falanga, M.; Palo, M.

    2006-08-01

    We analyze time series of Strombolian volcanic tremor, focusing our attention on the frequency band [0.1-0.5] Hz (very long period (VLP) tremor). Although this frequency band is largely affected by noise, we evidence two significant components by using Independent Component Analysis with the frequencies, respectively, of ~0.2 and ~0.4 Hz. We show that these components display wavefield features similar to those of the high frequency Strombolian signals (>0.5 Hz). In fact, they are radially polarised and located within the crater area. This characterization is lost when an enhancement of energy appears. In this case, the presence of microseismic noise becomes relevant. Investigating the entire large data set available, we determine how microseismic noise influences the signals. We ascribe the microseismic noise source to Scirocco wind. Moreover, our analysis allows one to evidence that the Strombolian conduit vibrates like the asymmetric cavity associated with musical instruments generating self-sustained tones.

  8. Rodent ultrasonic communication: Male prosocial 50-kHz ultrasonic vocalizations elicit social approach behavior in female rats (Rattus norvegicus).

    PubMed

    Willadsen, Maria; Seffer, Dominik; Schwarting, Rainer K W; Wöhr, Markus

    2014-02-01

    Rats emit distinct types of ultrasonic vocalizations (USV), which serve as situation-dependent affective signals with important communicative functions. Low-frequency 22-kHz USV typically occur in aversive situations, such as social defeat, whereas high-frequency 50-kHz USV can be observed in appetitive situations, like rough-and-tumble-play in juveniles or mating in adults. The 2 main USV types serve distinct communicative functions and induce call-specific behavioral responses in the receiver. While 22-kHz USV probably serve as alarm calls, 50-kHz USV appear to serve a prosocial communicative function in the sexual and the nonsexual context. In the sexual context, however, this view has recently been challenged by playback studies where only very limited behavioral changes were observed in response to prosocial 50-kHz USV. The aim of the present study was therefore to test whether female rats display social approach behavior in response to male prosocial 50-kHz USV by means of our established playback paradigm. To this aim, we exposed female rats to playback of the following 2 acoustic stimuli: (a) natural male 50-kHz USV and (b) time- and amplitude-matched white noise, with the latter serving as acoustic control for novelty-induced changes in behavior not linked to the communicative function of male prosocial 50-kHz USV. Our present findings show that female rats display high levels of social approach behavior in response to male prosocial 50-kHz USV, but not time- and amplitude-matched white noise, supporting the conclusion that male prosocial 50-kHz USV are likely to play an important role in establishing social proximity and possibly regulate mating behavior.

  9. A radio pulsar spinning at 716 Hz.

    PubMed

    Hessels, Jason W T; Ransom, Scott M; Stairs, Ingrid H; Freire, Paulo C C; Kaspi, Victoria M; Camilo, Fernando

    2006-03-31

    We have discovered a 716-hertz eclipsing binary radio pulsar in the globular cluster Terzan 5 using the Green Bank Telescope. It is the fastest spinning neutron star found to date, breaking the 24-year record held by the 642-hertz pulsar B1937+21. The difficulty in detecting this pulsar, because of its very low flux density and high eclipse fraction (approximately 40% of the orbit), suggests that even faster spinning neutron stars exist. If the pulsar has a mass less than twice the mass of the Sun, then its radius must be constrained by the spin rate to be <16 kilometers. The short period of this pulsar also constrains models that suggest that gravitational radiation, through an r-mode (Rossby wave) instability, limits the maximum spin frequency of neutron stars.

  10. A radio pulsar spinning at 716 Hz.

    PubMed

    Hessels, Jason W T; Ransom, Scott M; Stairs, Ingrid H; Freire, Paulo C C; Kaspi, Victoria M; Camilo, Fernando

    2006-03-31

    We have discovered a 716-hertz eclipsing binary radio pulsar in the globular cluster Terzan 5 using the Green Bank Telescope. It is the fastest spinning neutron star found to date, breaking the 24-year record held by the 642-hertz pulsar B1937+21. The difficulty in detecting this pulsar, because of its very low flux density and high eclipse fraction (approximately 40% of the orbit), suggests that even faster spinning neutron stars exist. If the pulsar has a mass less than twice the mass of the Sun, then its radius must be constrained by the spin rate to be <16 kilometers. The short period of this pulsar also constrains models that suggest that gravitational radiation, through an r-mode (Rossby wave) instability, limits the maximum spin frequency of neutron stars. PMID:16410486

  11. Doubly Fed Induction Generator in an Offshore Wind Power Plant Operated at Rated V/Hz: Preprint

    SciTech Connect

    Muljadi, E.; Singh, M.; Gevorgian, V.

    2012-06-01

    This paper introduces the concept of constant Volt/Hz operation of offshore wind power plants. The deployment of offshore WPPs requires power transmission from the plant to the load center inland. Since this power transmission requires submarine cables, there is a need to use High-Voltage Direct Current transmission, which is economical for transmission distances longer than 50 kilometers. In the concept presented here, the onshore substation is operated at 60 Hz synced with the grid, and the offshore substation is operated at variable frequency and voltage, thus allowing the WPP to be operated at constant Volt/Hz.

  12. The 40-Hz auditory steady-state response: a selective biomarker for cortical NMDA function.

    PubMed

    Sivarao, Digavalli V

    2015-05-01

    When subjected to a phasic input, sensory cortical neurons display a remarkable ability to entrain faithfully to the driving stimuli. The entrainment to rhythmic sound stimuli is often referred to as the auditory steady-state response (ASSR) and can be captured using noninvasive techniques, such as scalp-recorded electroencephalography (EEG). An ASSR to a driving frequency of approximately 40 Hz is particularly interesting in that it shows, in relative terms, maximal power, synchrony, and synaptic activity. Moreover, the 40-Hz ASSR has been consistently found to be abnormal in schizophrenia patients across multiple studies. The nature of the reported abnormality has been less consistent; while most studies report a deficit in entrainment, several studies have reported increased signal power, particularly when there are concurrent positive symptoms, such as auditory hallucinations. However, the neuropharmacological basis for the 40-Hz ASSR, as well as its dysfunction in schizophrenia, has been unclear until recently. On the basis of several recent reports, it is argued that the 40-Hz ASSR represents a specific marker for cortical NMDA transmission. If confirmed, the 40-Hz ASSR may be a simple and easy-to-access pharmacodynamic biomarker for testing the integrity of cortical NMDA neurotransmission that is robustly translational across species. PMID:25809615

  13. Deficits in the 30-Hz auditory steady-state response in patients with major depressive disorder.

    PubMed

    Chen, Jingjing; Gong, Qin; Wu, Fei

    2016-10-19

    The auditory steady-state response (ASSR) is an auditory evoked potential that occurs in response to periodically presented auditory stimuli. The ASSR has drawn attention as a biomarker of psychiatric disorders owing to its connection with neural oscillations as well as its easy and noninvasive recording. Abnormalities in the γ band ASSR have been found consistently in patients with schizophrenia and bipolar disorder. However, although major depressive disorder (MDD) is also part of the common psychiatric diseases, the relationship between the ASSR and MDD has not been characterized sufficiently. Thus, the aim of the present study was to examine the ASSRs from patients with MDD and compare them with those from healthy control (HC) participants. The experiment was designed to obtain the ASSRs elicited by 20-, 30-, and 40-Hz click trains. Patients and HCs were evaluated separately. The response power and phase synchronization were measured at each stimulation frequency. Patients with MDD showed significantly reduced ASSR power for 30-Hz stimuli compared with HC participants, whereas no significant differences in the power were observed at 20 and 40 Hz for patients with MDD. In addition, no significant difference in the phase synchronization was observed for 20-, 30-, and 40-Hz stimuli. Conclusively, patients with MDD were characterized by deficits in 30-Hz ASSR power, which may be associated with spontaneous γ activity dysfunction. The present findings suggest that ASSR could potentially be used as a biomarker for MDD. PMID:27563737

  14. Observations of High Frequency Harmonics of the Ionospheric Alfven Resonator

    NASA Astrophysics Data System (ADS)

    Mann, Ian; Usanova, Maria; Bortnik, Jacob; Milling, David; Kale, Andy; Shao, Leo; Miles, David; Rae, I. Jonathan

    We present observations of high frequency harmonics of the ionospheric Alfven Resonator (IAR). These are seen in the form of spectral resonance structures (SRS) recorded by a ground-based search coil magnetometer sampling at 100 samples/s at the Ministik Lake station at L=4.2 within the expanded CARISMA magnetometer array. Previous observational studies have indicated that such SRS are typically confined to frequencies <~5 Hz with only several SRS harmonics being observed. We report the first observations of clear and discrete SRS, which we believe are harmonics of the IAR, and which extend to around 20 Hz in at least 10-12 clear SRS harmonics. We additionally demonstrate the utility of the Bortnik et al. (2007) auto-detection algorithm, designed for Pc1 wavepackets, for characterising the properties of the IAR. Our results also indicate that the cavity supporting SRS in the IAR at this time must be structured to support and trap much higher frequency IAR harmonics than previously assumed. This impacts the potential importance of the IAR for magnetosphere-ionosphere coupling, especially in relation to the impacts of incident Alfven waves on the ionosphere including Alfvenic aurora. Our observations also highlight the potential value of IAR observations for diagnosing the structure of the topside ionosphere, not least using the observed structure of the SRS. These are the first mid-latitude observations demonstrating that the IAR can extend to frequencies beyond those of the lowest few harmonics of the Schumann resonances - significantly suggesting the possibility that the Schumann resonance modes and the IAR may be coupled. The in-situ structure of the IAR is also examined by combining satellite data with conjugate measurements from the ground, and the impacts of the IAR for magnetosphere-ionosphere-thermosphere coupling examined.

  15. 47 CFR 87.475 - Frequencies.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Management Office prior to each activation of the transmitter. (e) Frequencies available for differential GPS... stations for differential GPS data links. (1) The frequencies available are on 25 kHz centers with...

  16. 47 CFR 87.475 - Frequencies.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Management Office prior to each activation of the transmitter. (e) Frequencies available for differential GPS... stations for differential GPS data links. (1) The frequencies available are on 25 kHz centers with...

  17. 47 CFR 87.475 - Frequencies.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Management Office prior to each activation of the transmitter. (e) Frequencies available for differential GPS... stations for differential GPS data links. (1) The frequencies available are on 25 kHz centers with...

  18. 47 CFR 87.475 - Frequencies.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Management Office prior to each activation of the transmitter. (e) Frequencies available for differential GPS... stations for differential GPS data links. (1) The frequencies available are on 25 kHz centers with...

  19. 47 CFR 87.475 - Frequencies.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Management Office prior to each activation of the transmitter. (e) Frequencies available for differential GPS... stations for differential GPS data links. (1) The frequencies available are on 25 kHz centers with...

  20. The Effect of 10 Hz Repetitive Transcranial Magnetic Stimulation of Posterior Parietal Cortex on Visual Attention

    PubMed Central

    Dombrowe, Isabel; Juravle, Georgiana; Alavash, Mohsen; Gießing, Carsten; Hilgetag, Claus C.

    2015-01-01

    Repetitive transcranial magnetic stimulation (rTMS) of the posterior parietal cortex (PPC) at frequencies lower than 5 Hz transiently inhibits the stimulated area. In healthy participants, such a protocol can induce a transient attentional bias to the visual hemifield ipsilateral to the stimulated hemisphere. This bias might be due to a relatively less active stimulated hemisphere and a relatively more active unstimulated hemisphere. In a previous study, Jin and Hilgetag (2008) tried to switch the attention bias from the hemifield ipsilateral to the hemifield contralateral to the stimulated hemisphere by applying high frequency rTMS. High frequency rTMS has been shown to excite, rather than inhibit, the stimulated brain area. However, the bias to the ipsilateral hemifield was still present. The participants’ performance decreased when stimuli were presented in the hemifield contralateral to the stimulation site. In the present study we tested if this unexpected result was related to the fact that participants were passively resting during stimulation rather than performing a task. Using a fully crossed factorial design, we compared the effects of high frequency rTMS applied during a visual detection task and high frequency rTMS during passive rest on the subsequent offline performance in the same detection task. Our results were mixed. After sham stimulation, performance was better after rest than after task. After active 10 Hz rTMS, participants’ performance was overall better after task than after rest. However, this effect did not reach statistical significance. The comparison of performance after rTMS with task and performance after sham stimulation with task showed that 10 Hz stimulation significantly improved performance in the whole visual field. Thus, although we found a trend to better performance after rTMS with task than after rTMS during rest, we could not reject the hypothesis that high frequency rTMS with task and high frequency rTMS during rest

  1. Multi-mJ, kHz, ps deep-ultraviolet source.

    PubMed

    Chang, Chun-Lin; Krogen, Peter; Liang, Houkun; Stein, Gregory J; Moses, Jeffrey; Lai, Chien-Jen; Siqueira, Jonathas P; Zapata, Luis E; Kärtner, Franz X; Hong, Kyung-Han

    2015-02-15

    We demonstrate a 0.56-GW, 1-kHz, 4.2-ps, 2.74-mJ deep-ultraviolet (DUV) laser at ∼257.7  nm with a beam propagation factor (M2) of ∼2.54 from a frequency-quadrupled cryogenic multi-stage Yb-doped chirped-pulse amplifier. The frequency quadrupling is achieved using LiB3O5 and β-BaB2O4 crystals for near-infrared (NIR)-to-green and green-to-DUV conversion, respectively. An overall NIR-to-DUV efficiency of ∼10% has been achieved, which is currently limited by the thermal-induced phase mismatching and the DUV-induced degradation of transmittance. To the best of our knowledge, this is the highest peak-power picosecond DUV source from a diode-pumped solid-state laser operating at kHz repetition rates.

  2. Rats selectively bred for low levels of 50 kHz ultrasonic vocalizations exhibit alterations in early social motivation.

    PubMed

    Harmon, K M; Cromwell, H C; Burgdorf, J; Moskal, J R; Brudzynski, S M; Kroes, R A; Panksepp, J

    2008-05-01

    In rats, the rates of 50 kHz ultrasonic vocalizations (USVs) can be used as a selective breeding phenotype and variations in this phenotype can be an indicator of affective states. The 50 kHz USV is elicited by rewarding stimuli (e.g., food, sexual behavior) and therefore can express a positive affective state. Conversely, the 22 kHz USV is elicited by aversive stimuli (e.g., presence of a predator, social defeat) indicating a negative affective state. In the present study, we tested the effect of selectively breeding for 50 kHz USVs on a variety of maternal social/emotional behaviors in young rat pups (PND 10-12). These measures consisted of an assessment of isolation calls and conditioned odor preference paradigm. Results indicate that animals selected for low levels of 50 kHz USVs show the greatest alterations in social behaviors compared to the control animals. The low line animals had an increase in isolation calls tested during place preference conditioning and a decrease in 50 kHz ultrasonic calls in all conditions. These same low line animals failed to show a typical preference for a maternally-associated odor during the place preference test. The different social behaviors of the high line animals did not consistently vary from those of the control group. These results have important implications for the study of genetic and epigenetic mechanisms underlying emotional states, and possibly contribute to the research underlying the emotional changes in developmental disorders such as autistic spectrum disorder by providing a novel animal model that displays communication deficits that are interdependent with significant social behavioral impairments. PMID:18393285

  3. Cochlear nonlinearity between 500 and 8000 Hz in listeners with moderate cochlear hearing loss

    NASA Astrophysics Data System (ADS)

    Lopez-Poveda, Enrique A.; Plack, Christopher J.; Meddis, Ray; Blanco, Jose L.

    2001-05-01

    For two listeners with flat hearing loss, temporal masking curves (TMCs) were measured for probe frequencies (Fp) of 0.5, 1.0, 2.0, 4.0, and 8.0 kHz and masker frequencies of 0.5, 0.6, 0.7, 0.9, 1.0, 1.05, 1.1, and 1.2 Fp. From these, basilar membrane (BM) input/output (IO) functions and psychophysical tuning curves (PTCs) were derived and compared with corresponding data for normal-hearing listeners. Linear IO functions were observed for one ear only and for probe frequencies of 4 kHz and above. This result is consistent with the consequences of severe outer hair cell (OHC) damage on the BM response. Elsewhere, however, IO functions showed residual compression, with slopes in the compression region close to normal. This suggests that either the impairment relates mostly to inner hair cell (IHC) dysfunction, or that OHC dysfunction reduces the gain of the BM at low levels while maintaining the degree of maximum compression. The data suggest that the active and the passive BM mechanisms have different relative positions (in frequency) in the apical and the basal regions of the cochlea. Across probe frequencies, the slopes of the TMCs for off-frequency maskers are shallower for the impaired ears. It is considered that this possibly reflects IHC-related compression.

  4. Gamma (40-100 Hz) oscillation in the hippocampus of the behaving rat.

    PubMed

    Bragin, A; Jandó, G; Nádasdy, Z; Hetke, J; Wise, K; Buzsáki, G

    1995-01-01

    The cellular generation and spatial distribution of gamma frequency (40-100 Hz) activity was examined in the hippocampus of the awake rat. Field potentials and unit activity were recorded by multiple site silicon probes (5- and 16-site shanks) and wire electrode arrays. Gamma waves were highly coherent along the long axis of the dentate hilus, but average coherence decreased rapidly in the CA3 and CA1 directions. Analysis of short epochs revealed large fluctuations in coherence values between the dentate and CA1 gamma waves. Current source density analysis revealed large sinks and sources in the dentate gyrus with spatial distribution similar to the dipoles evoked by stimulation of the perforant path. The frequency changes of gamma and theta waves positively correlated (40-100 Hz and 5-10 Hz, respectively). Putative interneurons in the dentate gyrus discharged at gamma frequency and were phase-locked to the ascending part of the gamma waves recorded from the hilus. Following bilateral lesion of the entorhinal cortex the power and frequency of hilar gamma activity significantly decreased or disappeared. Instead, a large amplitude but slower gamma pattern (25-50 Hz) emerged in the CA3-CA1 network. We suggest that gamma oscillation emerges from an interaction between intrinsic oscillatory properties of interneurons and the network properties of the dentate gyrus. We also hypothesize that under physiological conditions the hilar gamma oscillation may be entrained by the entorhinal rhythm and that gamma oscillation in the CA3-CA1 circuitry is suppressed by either the hilar region or the entorhinal cortex.

  5. The crystal structure and morphology of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) p-xylene solvate: a joint experimental and simulation study.

    PubMed

    Shen, Fanfan; Lv, Penghao; Sun, Chenghui; Zhang, Rubo; Pang, Siping

    2014-01-01

    The crystal structure of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaiso-wurtzitane (CL-20) p-xylene solvate, and the solvent effects on the crystal faces of CL-20 were studied through a combined experimental and theoretical method. The properties were analyzed by thermogravimetry-differential scanning calorimetry (TG-DSC), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD).The growth morphology of CL-20p-xylene solvate crystal was predicted with a modified attachment energy model. The crystal structure of CL-20p-xylene solvate belonged to the Pbca space group with the unit cell parameters, a=8.0704(12) Å, b=13.4095(20) Å, c=33.0817(49) Å, and Z=4, which indicated that the p-xylene solvent molecules could enter the crystal lattice of CL-20 and thus the CL-20 p-xylene solvate is formed. According to the solvent-effected attachment energy calculations, (002) and (11-1) faces should not be visible at all, while the percentage area of the (011) face could be increased from 7.81% in vacuum to 12.51% in p-xylene solution. The predicted results from the modified attachment energy model agreed very well with the observed morphology of crystals grown from p-xylene solution. PMID:25401400

  6. Prevalence of Malocclusion among 10-12-year-old Schoolchildren in Kozhikode District, Kerala: An Epidemiological Study

    PubMed Central

    Jeseem, MT; Kumar, TV Anupam

    2016-01-01

    ABSTRACT Background: A malocclusion is an irregularity of the teeth or a malrelationship of the dental arches beyond the range of what is accepted as normal. Objectives: To determine the prevalence of malocclusion in children aged 10-12 years in Kozhikode district of Kerala, South India. Materials and methods: A descriptive cross-sectional study was conducted among schoolchildren aged 10-12 years in six schools in Kozhikode district of Kerala, South India. A total of 2,366 children satisfied the inclusion criteria. Occlusal characteristics like crossbite, open bite, deep bite, protrusion of teeth, midline deviations, midline diastema and tooth rotation were recorded. The data were tabulated and analyzed using Chi-square test. Results: The results revealed that the overall prevalence of malocclusion was 83.3%. Of this, 69.8% of the children had Angle’s class I malocclusion, 9.3% had class II malocclusion (division 1 = 8.85%, division 2 = 0.5%) and 4.1% had class III malocclusion; 23.2% showed an increased overjet (>3 mm), 0.4% reverse overjet, 35.6% increased overbite (>3 mm), 0.29% open bite, 7.2% crossbite with 4.6% crossbite of complete anterior teeth, 63.3% deviation of midline, 0.76% midline diastema and 3.25% rotated tooth. No significant differences in gender distributions of malocclusions were noted except for increased overjet and overbite. Conclusion: There is high prevalence of malocclusion among schoolchildren in Kozhikode district of Kerala. Early interception and early correction of these malocclusions will eliminate the potential irregularities and malpositions in the developing dentofacial complex. How to cite this article: Narayanan RK, Jeseem MT, Kumar TVA. Prevalence of Malocclusion among 10-12-year-old Schoolchildren in Kozhikode District, Kerala: An Epidemiological Study. Int J Clin Pediatr Dent 2016;9(1):50-55. PMID:27274156

  7. Simple sweep frequency generator

    NASA Astrophysics Data System (ADS)

    Yegorov, I.

    1985-01-01

    A sweep frequency generator is described whose center frequency can be varied from 10 kHz to 50 MHz, with seven 1 to 3 and 3 to 10 scales covering the 10 kHz to 30 MHz range and one 3 to 5 scale for the 30 to 50 MHz range. It consists of a tunable pulse generator with output voltage attenuator, a diode mixer for calibration, and a sawtooth voltage generator as a source of frequency deviation. The pulse generator is a multivibrator with two emitter coupled transistors and two diodes in the collector circuit of one. The first diode extends the tuning range and increases the frequency deviation, the second diode provides the necessary base bias to the other transistor. The pulse repetition rate is modulated either directly by the sweep voltage of the calibrating oscilloscope, this voltage being applied to the base of the transistor with the two diodes in its collector circuit through an additional attenuator or a special emitter follower, or by the separate sawtooth voltage generator. The latter is a conventional two transistor multivibrator and produces signals at any constant frequency within the 40 to 60 Hz range. The mixer receives unmodulated signals from a reference frequency source and produces different frequency signals which are sent through an RCR-filter to a calibrating oscilloscope.

  8. Unstable Isomer of C90 Fullerene Isolated as Chloro Derivatives, C90 (1)Cl10/12.

    PubMed

    Chilingarov, Norbert S; Troyanov, Sergey I

    2016-07-01

    High-temperature chlorination of C90 -containing fullerene fraction resulted in the isolation and X-ray structural characterization of C90 (1)Cl10/12 , the first derivatives of a relatively unstable isomer D5h -C90 (1) with a nanotubular shape. In the crystal structure, three isomers of both C90 (1)Cl10 and C90 (1)Cl12 with similar chlorination patterns co-crystallize in the same crystallographic site. Thus, in contrast to the previous reports, D5h -C90 (1) is present, though with a low abundance, in the fullerene soot produced by arc-discharge method with undoped graphite rods. PMID:27311795

  9. A novel particle separation technique using 20-kHz-order ultrasound irradiation in water

    NASA Astrophysics Data System (ADS)

    Muramatsu, Hiroya; Yanai, Sayuri; Mizushima, Yuki; Saito, Takayuki

    2015-12-01

    Ultrasound techniques such as washing, fine-particle manipulation and mixing have been investigated. MHz-band ultrasound was usually used in the previous work, and studies of kHz-order ultrasound are very rare. In the usual manipulation technique, μm- order particles are targeted due to wavelength limitations. We discovered an interesting phenomenon that holds promise for a novel particle separation technique using kHz-order ultrasound. Here, particles with sub-mm- or mm-order diameters were flocculated into a swarm in water irradiated by 20-kHz ultrasound. To develop a practical separation process, we investigated the stationary position and dia. of the particle swarms and the sound- pressure profiles in a vessel, as well as the flocculation mechanism, by varying the irradiation frequency, water level, particle diameter and particle amount. The primary stationary position corresponded to the wavelength calculated from the resonant frequency regardless of the particle diameter. Subtle changes in the frequency and water level resulted in a significant change in the stationary position. Based on these results, we propose a new separation process based on the particle diameter for sub-mm- or mm-order particles.

  10. Comparison of cardiac and 60 Hz magnetically induced electric fields measured in anesthetized rats

    SciTech Connect

    Miller, D.L.; Creim, J.A.

    1997-06-01

    Extremely low frequency magnetic fields interact with an animal by inducing internal electric fields, which are in addition to the normal endogenous fields present in living animals. Male rats weighing about 560 g each were anesthetized with ketamine and xylazine. Small incisions were made in the ventral body wall at the chest and upper abdomen to position a miniature probe for measuring internal electric fields. The calibration constant for the probe size was 5.7 mm, with a flat response from at least 12 Hz to 20 kHz. A cardiac signal, similar to the normal electrocardiogram with a heart rate of about 250 bpm, was readily obtained at the chest. Upon analysis of its spectrum, the cardiac field detected by the probe had a broad maximum at 32--95 Hz. When the rates were exposed to a 1 mT, 60 Hz magnetic field, a spike appeared in the spectrum at 60 Hz. The peak-to-peak magnitudes of electric fields associated with normal heart function were comparable to fields induced by a 1 mT magnetic field at 60 Hz for those positions measured on the body surface. Within the body, or in different directions relative to the applied field, the induced fields were reduced. The cardiac field increased near the heart, becoming much larger than the induced field. Thus, the cardiac electric field, together with the other endogenous fields, combine with induced electric fields and help to provide reference levels for the induced-field dosimetry of ELF magnetic field exposures of living animals.

  11. Buffer-gas-induced linewidth reduction of coherent dark resonances to below 50 Hz

    NASA Astrophysics Data System (ADS)

    Brandt, S.; Nagel, A.; Wynands, R.; Meschede, D.

    1997-08-01

    When neon is introduced as a buffer gas the interaction time of cesium atoms in a vapor cell with resonant laser beams is drastically increased. Using a pair of phase-locked lasers we have observed linewidths as narrow as 42 Hz for coherent dark resonances in a cesium vapor cell. We study the influence of power and pressure broadening and systematic shifts of the resonance frequency. Our experiments demonstrate that coherent dark resonances could rival direct radio-frequency precision measurements, which have a wide range of applications in physics.

  12. A microrod-resonator Brillouin laser with 240 Hz absolute linewidth

    NASA Astrophysics Data System (ADS)

    Loh, William; Becker, Joe; Cole, Daniel C.; Coillet, Aurelien; Baynes, Fred N.; Papp, Scott B.; Diddams, Scott A.

    2016-04-01

    We demonstrate an ultralow-noise microrod-resonator based laser that oscillates on the gain supplied by the stimulated Brillouin scattering optical nonlinearity. Microresonator Brillouin lasers are known to offer an outstanding frequency noise floor, which is limited by fundamental thermal fluctuations. Here, we show experimental evidence that thermal effects also dominate the close-to-carrier frequency fluctuations. The 6 mm diameter microrod resonator used in our experiments has a large optical mode area of ∼100 μm2, and hence its 10 ms thermal time constant filters the close-to-carrier optical frequency noise. The result is an absolute laser linewidth of 240 Hz with a corresponding white-frequency noise floor of 0.1 Hz2 Hz‑1. We explain the steady-state performance of this laser by measurements of its operation state and of its mode detuning and lineshape. Our results highlight a mechanism for noise that is common to many microresonator devices due to the inherent coupling between intracavity power and mode frequency. We demonstrate the ability to reduce this noise through a feedback loop that stabilizes the intracavity power.

  13. 60 HZ beam motion reduction at NSLS UV storage ring

    SciTech Connect

    Singh, O.V.

    1997-01-01

    A significant reduction in 60 hz beam motion has been achieved in the UV storage ring. From the wide band harmonic beam motion signal, 60 hz signal is extracted by tuned bandpass filter. This signal is processed by the phase and amplitude adjustment circuits and then, it is fed into the harmonic orbit generation circuits. Several harmonics, near the tune, were canceled by employing one circuit for each harmonic. The design and description of this experiment is given in this paper. The results showing reduction in beam motion at 60 hz are also provided.

  14. Intermittent 20-HZ-photic stimulation leads to a uniform reduction of alpha-global field power in healthy volunteers.

    PubMed

    Rau, R; Raschka, C; Koch, H J

    2001-01-01

    19-channel-EEGs were recorded from scalp surface of 30 healthy subjects (16m, 14f, mean age: 34 ys, SD: 11.7 ys) at rest and under IPS (Intermittent Photic Stimulation) at rates of 5, 10 and 20 Hertz (Hz). Digitalized data underwent spectral analysis with fast fourier transfomation (FFT) yielding the basis for the computation of global field power (GFP). For quantification GFP values in the frequency ranges of 5, 10 and 20 Hz at rest were divided by the corresponding data gained under IPS. While ratios from PDE data showed no stable parameter due to high interindividual variability, ratios of alpha-power turned out to be uniform in all subjects: IPS at 20 Hz always led to a suppression of alpha-power. Dividing alpha-GFP at rest by alpha-GFP under 20-Hz IPS thus resulted in a ratio < 1. We conclude that ratios from GFP data are a stable diagnostic paradigma. PMID:11811850

  15. Intermittent 20-HZ-photic stimulation leads to a uniform reduction of alpha-global field power in healthy volunteers.

    PubMed

    Rau, R; Raschka, C; Koch, H J

    2001-01-01

    19-channel-EEGs were recorded from scalp surface of 30 healthy subjects (16m, 14f, mean age: 34 ys, SD: 11.7 ys) at rest and under IPS (Intermittent Photic Stimulation) at rates of 5, 10 and 20 Hertz (Hz). Digitalized data underwent spectral analysis with fast fourier transfomation (FFT) yielding the basis for the computation of global field power (GFP). For quantification GFP values in the frequency ranges of 5, 10 and 20 Hz at rest were divided by the corresponding data gained under IPS. While ratios from PDE data showed no stable parameter due to high interindividual variability, ratios of alpha-power turned out to be uniform in all subjects: IPS at 20 Hz always led to a suppression of alpha-power. Dividing alpha-GFP at rest by alpha-GFP under 20-Hz IPS thus resulted in a ratio < 1. We conclude that ratios from GFP data are a stable diagnostic paradigma.

  16. 60 Hz electric field changes the membrane potential during burst phase in pancreatic β-cells: in silico analysis.

    PubMed

    Neves, Gesilda F; Silva, José R F; Moraes, Renato B; Fernandes, Thiago S; Tenorio, Bruno M; Nogueira, Romildo A

    2014-06-01

    The production, distribution and use of electricity can generate low frequency electric and magnetic fields (50-60 Hz). Considering that some studies showed adverse effects on pancreatic β-cells exposed to these fields; the present study aimed to analyze the effects of 60 Hz electric fields on membrane potential during the silent and burst phases in pancreatic β-cells using a mathematical model. Sinusoidal 60 Hz electric fields with amplitude ranging from 0.5 to 4 mV were applied on pancreatic β-cells model. The sinusoidal electric field changed burst duration, inter-burst intervals (silent phase) and spike sizes. The parameters above presented dose-dependent response with the voltage amplitude applied. In conclusion, theoretical analyses showed that a 60 Hz electric field with low amplitudes changes the membrane potential in pancreatic β-cells.

  17. CHARACTERIZING INTERMITTENCY OF 4-Hz QUASI-PERIODIC OSCILLATION IN XTE J1550–564 USING HILBERT–HUANG TRANSFORM

    SciTech Connect

    Su, Yi-Hao; Chou, Yi; Hu, Chin-Ping; Yang, Ting-Chang E-mail: yichou@astro.ncu.edu.tw

    2015-12-10

    We present time-frequency analysis results based on the Hilbert–Huang transform (HHT) for the evolution of a 4-Hz low-frequency quasi-periodic oscillation (LFQPO) around the black hole X-ray binary XTE J1550–564. The origin of LFQPOs is still debated. To understand the cause of the peak broadening, we utilized a recently developed time-frequency analysis, HHT, for tracking the evolution of the 4-Hz LFQPO from XTE J1550–564. By adaptively decomposing the ∼4-Hz oscillatory component from the light curve and acquiring its instantaneous frequency, the Hilbert spectrum illustrates that the LFQPO is composed of a series of intermittent oscillations appearing occasionally between 3 and 5 Hz. We further characterized this intermittency by computing the confidence limits of the instantaneous amplitudes of the intermittent oscillations, and constructed both the distributions of the QPO’s high- and low-amplitude durations, which are the time intervals with and without significant ∼4-Hz oscillations, respectively. The mean high-amplitude duration is 1.45 s and 90% of the oscillation segments have lifetimes below 3.1 s. The mean low-amplitude duration is 0.42 s and 90% of these segments are shorter than 0.73 s. In addition, these intermittent oscillations exhibit a correlation between the oscillation’s rms amplitude and mean count rate. This correlation could be analogous to the linear rms-flux relation found in the 4-Hz LFQPO through Fourier analysis. We conclude that the LFQPO peak in the power spectrum is broadened owing to intermittent oscillations with varying frequencies, which could be explained by using the Lense–Thirring precession model.

  18. Characterizing Intermittency of 4-Hz Quasi-periodic Oscillation in XTE J1550-564 Using Hilbert-Huang Transform

    NASA Astrophysics Data System (ADS)

    Su, Yi-Hao; Chou, Yi; Hu, Chin-Ping; Yang, Ting-Chang

    2015-12-01

    We present time-frequency analysis results based on the Hilbert-Huang transform (HHT) for the evolution of a 4-Hz low-frequency quasi-periodic oscillation (LFQPO) around the black hole X-ray binary XTE J1550-564. The origin of LFQPOs is still debated. To understand the cause of the peak broadening, we utilized a recently developed time-frequency analysis, HHT, for tracking the evolution of the 4-Hz LFQPO from XTE J1550-564. By adaptively decomposing the ˜4-Hz oscillatory component from the light curve and acquiring its instantaneous frequency, the Hilbert spectrum illustrates that the LFQPO is composed of a series of intermittent oscillations appearing occasionally between 3 and 5 Hz. We further characterized this intermittency by computing the confidence limits of the instantaneous amplitudes of the intermittent oscillations, and constructed both the distributions of the QPO’s high- and low-amplitude durations, which are the time intervals with and without significant ˜4-Hz oscillations, respectively. The mean high-amplitude duration is 1.45 s and 90% of the oscillation segments have lifetimes below 3.1 s. The mean low-amplitude duration is 0.42 s and 90% of these segments are shorter than 0.73 s. In addition, these intermittent oscillations exhibit a correlation between the oscillation’s rms amplitude and mean count rate. This correlation could be analogous to the linear rms-flux relation found in the 4-Hz LFQPO through Fourier analysis. We conclude that the LFQPO peak in the power spectrum is broadened owing to intermittent oscillations with varying frequencies, which could be explained by using the Lense-Thirring precession model.

  19. High-sensitivity cooled coil system for nuclear magnetic resonance in kHz range

    SciTech Connect

    Lin, Tingting; Zhao, Jing; Zhang, Yi; Krause, Hans-Joachim; Lee, Yong-Ho; Lin, Jun

    2014-11-15

    In several low-field Nuclear Magnetic Resonance (LF-NMR) and surface nuclear magnetic resonance applications, i.e., in the frequency range of kHz, high sensitivity magnetic field detectors are needed. Usually, low-T{sub c} superconducting quantum interference devices (SQUIDs) with a high field sensitivity of about 1 fT/Hz{sup 1/2} are employed as detectors. Considering the flux trapping and operational difficulties associated with low-T{sub c} SQUIDs, we designed and fabricated liquid-nitrogen-cooled Cu coils for NMR detection in the kHz range. A cooled coil system consisting of a 9-cm diameter Cu coil and a low noise preamplifier was systematically investigated and reached a sensitivity of 2 fT/Hz{sup 1/2} at 77 K, which is 3 times better compared to the sensitivity at 300 K. A Q-switch circuit as an essential element for damping the ringing effects of the pickup coil was developed to acquire free induction decay signals of a water sample with minimum loss of signal. Our studies demonstrate that cooled Cu coils, if designed properly, can provide a comparable sensitivity to low-T{sub c} SQUIDs.

  20. Dynamic nuclear polarization at 40 kHz magic angle spinning.

    PubMed

    Chaudhari, Sachin R; Berruyer, Pierrick; Gajan, David; Reiter, Christian; Engelke, Frank; Silverio, Daniel L; Copéret, Christophe; Lelli, Moreno; Lesage, Anne; Emsley, Lyndon

    2016-04-21

    DNP-enhanced solid-state NMR spectroscopy under magic angle spinning (MAS) is rapidly developing into a powerful analytical tool to investigate the structure of a wide range of solid materials, because it provides unsurpassed sensitivity gains. Most developments and applications of DNP MAS NMR were so far reported at moderate spinning frequencies (up to 14 kHz using 3.2 mm rotors). Here, using a 1.3 mm MAS DNP probe operating at 18.8 T and ∼100 K, we show that signal amplification factors can be increased by up to a factor two when using smaller volume rotors as compared to 3.2 mm rotors, and report enhancements of around 60 over a range of sample spinning rates from 10 to 40 kHz. Spinning at 40 kHz is also shown to increase (29)Si coherence lifetimes by a factor three as compared to 10 kHz, substantially increasing sensitivity in CPMG type experiments. The contribution of quenching effects to the overall sensitivity gain at very fast MAS is evaluated, and applications are reported on a functionalised mesostructured organic-inorganic material.

  1. Extension of non-invasive EEG into the kHz range for evoked thalamocortical activity by means of very low noise amplifiers.

    PubMed

    Scheer, H J; Fedele, T; Curio, G; Burghoff, M

    2011-12-01

    Ultrafast electroencephalographic signals, having frequencies above 500 Hz, can be observed in somatosensory evoked potential measurements. Usually, these recordings have a poor signal-to-noise ratio (SNR) because weak signals are overlaid by intrinsic noise of much higher amplitude like that generated by biological sources and the amplifier. As an example, recordings at the scalp taken during electrical stimulation of the median nerve show a 600 Hz burst with submicro-volt amplitudes which can be extracted from noise by the use of massive averaging and digital signal processing only. We have investigated this signal by means of a very low noise amplifier made in-house (minimal voltage noise 2.7 nV Hz(-1/2), FET inputs). We examined how the SNR of the data is altered by the bandwidth and the use of amplifiers with different intrinsic amplifier noise levels of 12 and 4.8 nV Hz(-1/2), respectively. By analyzing different frequency contributions of the signal, we found an extremely weak 1 kHz component superimposed onto the well-known 600 Hz burst. Previously such high-frequency electroencephalogram responses around 1 kHz have only been observed by deep brain electrodes implanted for tremor therapy of Parkinson patients. For the non-invasive measurement of such signals, we recommend that amplifier noise should not exceed 4 nV Hz(-1/2).

  2. 47 CFR 15.33 - Frequency range of radiated measurements.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... level of radiated emissions within the frequency range 9 kHz to 30 MHz, such as a CB receiver or a device designed to conduct its radio frequency emissions via connecting wires or cables, e.g., a carrier... used in the device, without going below 9 kHz (25 MHz for CB receivers), up to the frequency shown...

  3. 47 CFR 15.33 - Frequency range of radiated measurements.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... level of radiated emissions within the frequency range 9 kHz to 30 MHz, such as a CB receiver or a device designed to conduct its radio frequency emissions via connecting wires or cables, e.g., a carrier... used in the device, without going below 9 kHz (25 MHz for CB receivers), up to the frequency shown...

  4. 47 CFR 15.33 - Frequency range of radiated measurements.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... level of radiated emissions within the frequency range 9 kHz to 30 MHz, such as a CB receiver or a device designed to conduct its radio frequency emissions via connecting wires or cables, e.g., a carrier... used in the device, without going below 9 kHz (25 MHz for CB receivers), up to the frequency shown...

  5. 47 CFR 15.33 - Frequency range of radiated measurements.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... level of radiated emissions within the frequency range 9 kHz to 30 MHz, such as a CB receiver or a device designed to conduct its radio frequency emissions via connecting wires or cables, e.g., a carrier... used in the device, without going below 9 kHz (25 MHz for CB receivers), up to the frequency shown...

  6. Colorimetric Detection of Some Highly Hydrophobic Flavonoids Using Polydiacetylene Liposomes Containing Pentacosa-10,12-diynoyl Succinoglycan Monomers

    PubMed Central

    Yun, Deokgyu; Jeong, Daham; Cho, Eunae; Jung, Seunho

    2015-01-01

    Flavonoids are a group of plant secondary metabolites including polyphenolic molecules, and they are well known for antioxidant, anti-allergic, anti-inflammatory and anti-viral propertied. In general, flavonoids are detected with various non-colorimetric detection methods such as column liquid chromatography, thin-layer chromatography, and electrochemical analysis. For the first time, we developed a straightforward colorimetric detection system allowing recognition of some highly hydrophobic flavonoids such as alpha-naphthoflavone and beta-naphthoflavone, visually using 10,12-pentacosadiynoic acid (PCDA) derivatized with succinoglycan monomers isolated from Sinorhizobium meliloti. Besides changes in visible spectrum, we also demonstrate fluorescence changes using our detection system in the presence of those flavonoids. The succinoglycan monomers attached to PCDA molecules may function as an unstructured molecular capturer for some highly hydrophobic flavonoids by hydrophobic interactions, and transmit their molecular interactions as a color change throughout the PCDA liposome. PMID:26600071

  7. Surface complexation studied via combined grazing-incidence EXAFS and surface diffraction: Arsenate on hematite (0001) and (10-12)

    USGS Publications Warehouse

    Waychunas, G.; Trainor, T.; Eng, P.; Catalano, J.; Brown, G.; Davis, J.; Rogers, J.; Bargar, J.

    2005-01-01

    X-ray diffraction [crystal-truncation-rod (CTR)] studies of the surface structure of moisture-equilibrated hematite reveal sites for complexation not present on the bulk oxygen-terminated surface, and impose constraints on the types of inner-sphere sorption topologies. We have used this improved model of the hematite surface to analyze grazing-incidence EXAFS results for arsenate sorption on the c(0001) and r(10-12) surfaces measured in two electric vector polarizations. This work shows that the reconfiguration of the surface under moist conditions is responsible for an increased adsorption density of arsenate complexes on the (0001) surface relative to predicted ideal termination, and an abundance of "edge-sharing" bidentate complexes on both studied surfaces. We consider possible limitations on combining the methods due to differing surface sensitivities, and discuss further analysis possibilities using both methods. ?? Springer-Verlag 2005.

  8. 47 CFR 18.301 - Operating frequencies.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 1 2013-10-01 2013-10-01 false Operating frequencies. 18.301 Section 18.301... Standards § 18.301 Operating frequencies. ISM equipment may be operated on any frequency above 9 kHz except as indicated in § 18.303. The following frequency bands, in accordance with § 2.106 of the rules,...

  9. 47 CFR 18.301 - Operating frequencies.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 1 2012-10-01 2012-10-01 false Operating frequencies. 18.301 Section 18.301... Standards § 18.301 Operating frequencies. ISM equipment may be operated on any frequency above 9 kHz except as indicated in § 18.303. The following frequency bands, in accordance with § 2.106 of the rules,...

  10. 47 CFR 18.301 - Operating frequencies.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 1 2014-10-01 2014-10-01 false Operating frequencies. 18.301 Section 18.301... Standards § 18.301 Operating frequencies. ISM equipment may be operated on any frequency above 9 kHz except as indicated in § 18.303. The following frequency bands, in accordance with § 2.106 of the rules,...

  11. 47 CFR 18.301 - Operating frequencies.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false Operating frequencies. 18.301 Section 18.301... Standards § 18.301 Operating frequencies. ISM equipment may be operated on any frequency above 9 kHz except as indicated in § 18.303. The following frequency bands, in accordance with § 2.106 of the rules,...

  12. 47 CFR 18.301 - Operating frequencies.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 1 2011-10-01 2011-10-01 false Operating frequencies. 18.301 Section 18.301... Standards § 18.301 Operating frequencies. ISM equipment may be operated on any frequency above 9 kHz except as indicated in § 18.303. The following frequency bands, in accordance with § 2.106 of the rules,...

  13. Reliability of electric response audiometry using 80 Hz auditory steady-state responses.

    PubMed

    Kaf, Wafaa A; Sabo, Diane L; Durrant, John D; Rubinstein, Elaine

    2006-08-01

    The reliability of the Auditory Steady State Response (ASSR) has not been thoroughly evaluated despite its recent application as a clinical tool for threshold estimation. The purpose of this study was to examine test-retest (TR) reliability of ASSR threshold estimates in an empirical research design. The ASSR, tested using modulation frequencies approximately 80 Hz and above, was evaluated against pure tone audiometry (PTA), and the slow vertex potential (SVP, N1-P2). Sixteen normal-hearing young female adults were tested twice, one week apart. Varying degrees of sensorineural hearing loss of a notched configuration were simulated with filtered masking noise. Test-retest reliability was assessed using Pearson-product moment correlation analysis, supplemented by other post-hoc analyses. Results demonstrated moderately strong TR reliability for ASSR at 1000, 2000 and 4000 Hz (r = 0.83-0.93); however, the reliability of ASSR at 500 Hz was weaker (r = 0.75). Results suggest that ASSR-ERA is a reliable test at mid-high frequencies, at least with the configuration and degrees of simulated sensorineural hearing loss examined in this study. PMID:17005490

  14. Continuous hydroxyl radical planar laser imaging at 50 kHz repetition rate.

    PubMed

    Hammack, Stephen; Carter, Campbell; Wuensche, Clemens; Lee, Tonghun

    2014-08-10

    This study demonstrates high-repetition-rate planar laser-induced fluorescence (PLIF) imaging of hydroxyl radicals (OH) in flames at a continuous framing rate of 50 kHz. A frequency-doubled dye laser is pumped by the second harmonic of an Nd:YAG laser to generate laser radiation near 283 nm with a pulse width of 8 ns and rate of 50 kHz. Fluorescence is recorded by a two-stage image intensifier and complementary metal-oxide-semiconductor camera. The average power of the 283 nm beam reaches 7 W, yielding a pulse energy of 140 μJ. Both a Hencken burner and a DC transient-arc plasmatron are used to produce premixed CH4/air flames to evaluate the OH PLIF system. The average signal-to-noise ratio for the Hencken burner flame is greater than 20 near the flame front and greater than 10 further downstream in a region of the flame near equilibrium. Image sequences of the DC plasmatron discharge clearly illustrate development and evolution of flow features with signal levels comparable to those in the Hencken burner. The results are a demonstration of the ability to make high-fidelity OH PLIF measurements at 50 kHz using a Nd:YAG-pumped, frequency-doubled dye laser. PMID:25320935

  15. Reliability of electric response audiometry using 80 Hz auditory steady-state responses.

    PubMed

    Kaf, Wafaa A; Sabo, Diane L; Durrant, John D; Rubinstein, Elaine

    2006-08-01

    The reliability of the Auditory Steady State Response (ASSR) has not been thoroughly evaluated despite its recent application as a clinical tool for threshold estimation. The purpose of this study was to examine test-retest (TR) reliability of ASSR threshold estimates in an empirical research design. The ASSR, tested using modulation frequencies approximately 80 Hz and above, was evaluated against pure tone audiometry (PTA), and the slow vertex potential (SVP, N1-P2). Sixteen normal-hearing young female adults were tested twice, one week apart. Varying degrees of sensorineural hearing loss of a notched configuration were simulated with filtered masking noise. Test-retest reliability was assessed using Pearson-product moment correlation analysis, supplemented by other post-hoc analyses. Results demonstrated moderately strong TR reliability for ASSR at 1000, 2000 and 4000 Hz (r = 0.83-0.93); however, the reliability of ASSR at 500 Hz was weaker (r = 0.75). Results suggest that ASSR-ERA is a reliable test at mid-high frequencies, at least with the configuration and degrees of simulated sensorineural hearing loss examined in this study.

  16. 1 Hz linewidth Ti:sapphire laser as local oscillator for (40)Ca(+) optical clocks.

    PubMed

    Bian, Wu; Huang, Yao; Guan, Hua; Liu, Peiliang; Ma, Longsheng; Gao, Kelin

    2016-06-01

    A Ti:sapphire laser at 729 nm is frequency stabilized to an ultra-stable ultra-low thermal expansion coefficient (ULE) cavity by means of Pound-Drever-Hall method. An acousto-optic modulator is used as the fast frequency feedback component. 1 Hz linewidth and 2 × 10(-15) frequency stability at 1-100 s are characterized by optical beating with a separated Fabry-Perot cavity stabilized diode laser. Compared to the universal method that the error signal feedback to inject current of a diode laser, this scheme is demonstrated to be simple and also effective for linewidth narrowing. The temperature of zero coefficient of the thermal expansion of the ULE cavity is measured with the help of a femto-second frequency comb. And the performance of the laser is well defined by locking it to the unperturbed clock transition line-center of 4 S1/2-3 D5/2 clock transition of a single laser cooled (40)Ca(+) ion. A Fourier-transform limited resonance of 6 Hz (Δv/v = 1.5 × 10(-14)) is observed. This laser is also used as the local oscillator for the comparison experiment of two (40)Ca(+) ion optical clocks and improves the stability of comparison for an order of magnitude better than the previous results.

  17. 1 Hz linewidth Ti:sapphire laser as local oscillator for (40)Ca(+) optical clocks.

    PubMed

    Bian, Wu; Huang, Yao; Guan, Hua; Liu, Peiliang; Ma, Longsheng; Gao, Kelin

    2016-06-01

    A Ti:sapphire laser at 729 nm is frequency stabilized to an ultra-stable ultra-low thermal expansion coefficient (ULE) cavity by means of Pound-Drever-Hall method. An acousto-optic modulator is used as the fast frequency feedback component. 1 Hz linewidth and 2 × 10(-15) frequency stability at 1-100 s are characterized by optical beating with a separated Fabry-Perot cavity stabilized diode laser. Compared to the universal method that the error signal feedback to inject current of a diode laser, this scheme is demonstrated to be simple and also effective for linewidth narrowing. The temperature of zero coefficient of the thermal expansion of the ULE cavity is measured with the help of a femto-second frequency comb. And the performance of the laser is well defined by locking it to the unperturbed clock transition line-center of 4 S1/2-3 D5/2 clock transition of a single laser cooled (40)Ca(+) ion. A Fourier-transform limited resonance of 6 Hz (Δv/v = 1.5 × 10(-14)) is observed. This laser is also used as the local oscillator for the comparison experiment of two (40)Ca(+) ion optical clocks and improves the stability of comparison for an order of magnitude better than the previous results. PMID:27370440

  18. 1 Hz linewidth Ti:sapphire laser as local oscillator for 40Ca+ optical clocks

    NASA Astrophysics Data System (ADS)

    Bian, Wu; Huang, Yao; Guan, Hua; Liu, Peiliang; Ma, Longsheng; Gao, Kelin

    2016-06-01

    A Ti:sapphire laser at 729 nm is frequency stabilized to an ultra-stable ultra-low thermal expansion coefficient (ULE) cavity by means of Pound-Drever-Hall method. An acousto-optic modulator is used as the fast frequency feedback component. 1 Hz linewidth and 2 × 10-15 frequency stability at 1-100 s are characterized by optical beating with a separated Fabry-Perot cavity stabilized diode laser. Compared to the universal method that the error signal feedback to inject current of a diode laser, this scheme is demonstrated to be simple and also effective for linewidth narrowing. The temperature of zero coefficient of the thermal expansion of the ULE cavity is measured with the help of a femto-second frequency comb. And the performance of the laser is well defined by locking it to the unperturbed clock transition line-center of 4 S1/2-3 D5/2 clock transition of a single laser cooled 40Ca+ ion. A Fourier-transform limited resonance of 6 Hz (Δv/v = 1.5 × 10-14) is observed. This laser is also used as the local oscillator for the comparison experiment of two 40Ca+ ion optical clocks and improves the stability of comparison for an order of magnitude better than the previous results.

  19. Tunable mechanical monolithic sensor with interferometric readout for low frequency seismic noise measurement

    NASA Astrophysics Data System (ADS)

    Acernese, F.; De Rosa, R.; Giordano, G.; Romano, R.; Barone, F.

    2008-10-01

    This paper describes a mechanical horizontal monolithic sensor for geophysical applications developed at the University of Salerno. The instrument is basically a monolithic tunable folded pendulum, shaped with precision machining and electric-discharge-machining, that can be used both as seismometer and, in a force-feedback configuration, as accelerometer. It is a very compact instrument, very sensitive in the low-frequency seismic noise band, with a very good immunity to environmental noises, whose main characteristics are the tunability of the resonance frequency and the integrated laser optical readout, consisting of an optical lever and an interferometer. The theoretical sensitivity curves are in a very good agreement with the measurements. A direct comparison of its performances with the STS-2 ones shows that better performances have been reached with the interferometric readout (~10-12 m/square root Hz in the band 10-1 ÷10Hz as seismometer. The first results as accelerometer (force feed-back configuration) are also presented and discussed.

  20. Tunable mechanical monolithic horizontal accelerometer for low frequency seismic noise measurement

    NASA Astrophysics Data System (ADS)

    Acernese, F.; De Rosa, R.; Giordano, G.; Romano, R.; Barone, F.

    2009-03-01

    This paper describes a mechanical horizontal monolithic sensor for geophysical applications developed at the University of Salerno. The instrument is basically a monolithic tunable folded pendulum, shaped with precision machining and electric-discharge-machining, that can be used both as seismometer and, in a force-feedback configuration, as accelerometer. It is a very compact instrument, very sensitive in the low-frequency seismic noise band, with a very good immunity to environmental noises, whose main characteristics are the tunability of the resonance frequency and the integrated laser optical readout, consisting of an optical lever and an interferometer. The theoretical sensitivity curves are in a very good agreement with the measurements. A direct comparison of its performances with the STS-2 ones shows that better performances have been reached with the interferometric readout (~ 10-12 m/ √ Hz in the band 10-1 ÷ 10Hz as seismometer. Finally, the first results as accelerometer (force feed-back configuration) are also presented and discussed.

  1. Performance of a 30-kV, 1-kHz, nanosecond source

    SciTech Connect

    Cravey, W.R.; Freytag, K.; Goerz, D.

    1992-06-01

    An existing pulser at LLNL was modified to increase its repetition rate to 1000 Hz. Spark gap recovery measurements were made for both the Marx and the Blumlein output switches. Recovery times of less than 1 ms were recorded without gas flow in the switch chambers. Low pressure synthetic air was used as the switch dielectric. Longer recovery times were necessary to over-voltage the switch. The output of the pulser was used to drive a log-periodic-dipole-array. Measurements were made on the transmitted pulses in an anechoic chamber and yielded a center frequency of 80 MHz. This paper describes the modifications made on the pulse generator, discusses the spark gap recovery data, and summarizes the performance of the pulser at 1 kHz. In addition, a brief description of the antenna is given along with the field measurements that were made in the EMPEROR facility.

  2. Somatotopic source arrangement of 600 Hz oscillatory magnetic fields at the human primary somatosensory hand cortex.

    PubMed

    Curio, G; Mackert, B M; Burghoff, M; Neumann, J; Nolte, G; Scherg, M; Marx, P

    1997-10-01

    Based on low-noise superconducting quantum interference devices (SQUIDs) magnetoencephalography allows the non-invasive detection of low-amplitude high-frequency brain responses evoked about 20 ms after electric hand nerve stimulation. The main spectral energy of these brief oscillatory bursts (near 600 Hz) is in the range typical for rapidly repeated action potentials. Here, the magnetic fields of median and ulnar nerve evoked 600 Hz bursts are shown to exhibit a somatotopic arrangement at the primary somatosensory hand cortex closely resembling that of the concomitant postsynaptic primary cortical response (¿N20m'). Two possible burst generators are discussed: (1) repetitive spike volleys conducted along the terminal segments of somatotopically arranged thalamocortical axons, and (2) early intracortical spike activity in nerve-specific subterritories of the 3b hand area.

  3. Effect of infrasound on cochlear damage from exposure to a 4-kHz octave band of noise

    PubMed Central

    Harding, Gary W.; Bohne, Barbara A.; Lee, Steve C.; Salt, Alec N.

    2008-01-01

    Infrasound (i.e., < 20 Hz for humans; < 100 Hz for chinchillas) is not audible, but exposure to high levels of infrasound will produce large movements of cochlear fluids. We speculated that high-level infrasound might bias the basilar membrane and perhaps be able to minimize noise-induced hearing loss. Chinchillas were simultaneously exposed to a 30 Hz tone at 100 dB SPL and a 4-kHz OBN at either 108 dB SPL for 1.75 h or 86 dB SPL for 24 h. For each animal, the tympanic membrane (TM) in one ear was perforated (~1 mm2) prior to exposure to attenuate infrasound transmission to that cochlea by about 50 dB SPL. Controls included animals that were exposed to the infrasound only or the 4-kHz OBN only. ABR threshold shifts (TSs) and DPOAE level shifts (LSs) were determined pre- and post-TM-perforation and immediately post-exposure, just before cochlear fixation. The cochleae were dehydrated, embedded in plastic, and dissected into flat preparations of the organ of Corti (OC). Each dissected segment was evaluated for losses of inner hair cells (IHCs) and outer hair cells (OHCs). For each chinchilla, the magnitude and pattern of functional and hair cell losses were compared between their right and left cochleae. The TM perforation produced no ABR TS across frequency but did produce a 10–21 dB DPOAE LS from 0.6–2 kHz. The infrasound exposure alone resulted in a 10–20 dB ABR TS at and below 2 kHz, no DPOAE LS and no IHC or OHC losses. Exposure to the 4-kHz OBN alone at 108 dB produced a 10–50 dB ABR TS for 0.5–12 kHz, a 10–60 dB DPOAE LS for 0.6–16 kHz and severe OHC loss in the middle of the first turn. When infrasound was present during exposure to the 4-kHz OBN at 108 dB, the functional losses and OHC losses extended much further toward the apical and basal tips of the OC than in cochleae exposed to the 4-kHz OBN alone. Exposure to only the 4-kHz OBN at 86 dB produces a 10–40 dB ABR TS for 3–12 kHz and 10–30 dB DPOAE LS for 3–8 kHz but little or no

  4. Coherent 40-Hz Oscillation Characterizes Dream State in Humans

    NASA Astrophysics Data System (ADS)

    Llinas, Rodolfo; Ribary, Urs

    1993-03-01

    Magnetic recording from five normal human adults demonstrates large 40-Hz coherent magnetic activity in the awake and in rapid-eye-movement (REM) sleep states that is very reduced during delta sleep (deep sleep characterized by delta waves in the electroencephalogram). This 40-Hz magnetic oscillation has been shown to be reset by sensory stimuli in the awake state. Such resetting is not observed during REM or delta sleep. The 40 Hz in REM sleep is characterized, as is that in the awake state, by a fronto-occiptal phase shift over the head. This phase shift has a maximum duration of thickapprox12-13 msec. Because 40-Hz oscillation is seen in wakefulness and in dreaming, we propose it to be a correlate of cognition, probably resultant from coherent 40-Hz resonance between thalamocortical-specific and nonspecific loops. Moreover, we proposed that the specific loops give the content of cognition, and a nonspecific loop gives the temporal binding required for the unity of cognitive experience.

  5. High spectral purity Kerr frequency comb radio frequency photonic oscillator

    PubMed Central

    Liang, W.; Eliyahu, D.; Ilchenko, V. S.; Savchenkov, A. A.; Matsko, A. B.; Seidel, D.; Maleki, L.

    2015-01-01

    Femtosecond laser-based generation of radio frequency signals has produced astonishing improvements in achievable spectral purity, one of the basic features characterizing the performance of an radio frequency oscillator. Kerr frequency combs hold promise for transforming these lab-scale oscillators to chip-scale level. In this work we demonstrate a miniature 10 GHz radio frequency photonic oscillator characterized with phase noise better than −60 dBc Hz−1 at 10 Hz, −90 dBc Hz−1 at 100 Hz and −170 dBc Hz−1 at 10 MHz. The frequency stability of this device, as represented by Allan deviation measurements, is at the level of 10−10 at 1–100 s integration time—orders of magnitude better than existing radio frequency photonic devices of similar size, weight and power consumption. PMID:26260955

  6. Laser frequency offset synthesizer

    NASA Astrophysics Data System (ADS)

    Lewis, D. A.; Evans, R. M.; Finn, M. A.

    1985-01-01

    A method is reported for locking the frequency difference of two lasers with an accuracy of 0.5 kHz or less over a one-second interval which is simple, stable, and relatively free from systematic errors. Two 633 nm He-Ne lasers are used, one with a fixed frequency and the other tunable. The beat frequency between the lasers is controlled by a voltage applied to a piezoelectric device which varies the cavity length of the tunable laser. This variable beat frequency, scaled by a computer-controlled modulus, is equivalent to a synthesizer. This approach eliminates the need for a separate external frequency synthesizer; furthermore, the phase detection process occurs at a relatively low frequency, making the required electronics simple and straightforward.

  7. Detection and temporal coherence of p-modes below 1.4 mHz

    NASA Astrophysics Data System (ADS)

    Eff-Darwich, A.; Régulo, C.; Korzennik, S. G.; Pérez Hernández, F.; Roca Cortés, T.

    2008-06-01

    Data collected recently by the helioseismic experiments aboard the SOHO spacecraft have allowed the detection of low degree p-modes with increasingly lower order n. In particular, the GOLF experiment is currently able to unambiguously identify low degree modes with frequencies as low as 1.3 mHz. The detection of p-modes with very low frequency ({i.e.}, low n), is difficult due to the low signal-to-noise ratio in this spectral region and its contamination by solar signals that are not of acoustic origin. To address this problem without using any theoretical a priory, we propose a methodology that relies only on the inversion of observed values to define a spectral window for the expected locations of these low frequency modes. The application of this method to 2920-day-long GOLF observations is presented and its results discussed.

  8. Three-dimensional magnetic cloak working from d.c. to 250 kHz.

    PubMed

    Zhu, Jianfei; Jiang, Wei; Liu, Yichao; Yin, Ge; Yuan, Jun; He, Sailing; Ma, Yungui

    2015-01-01

    Invisible cloaking is one of the major outcomes of the metamaterial research, but the practical potential, in particular for high frequencies (for example, microwave to visible light), is fatally challenged by the complex material properties they usually demand. On the other hand, it will be advantageous and also technologically instrumental to design cloaking devices for applications at low frequencies where electromagnetic components are favourably uncoupled. In this work, we vastly develop the bilayer approach to create a three-dimensional magnetic cloak able to work in both static and dynamic fields. Under the quasi-static approximation, we demonstrate a perfect magnetic cloaking device with a large frequency band from 0 to 250 kHz. The practical potential of our device is experimentally verified by using a commercial metal detector, which may lead us to having a real cloaking application where the dynamic magnetic field can be manipulated in desired ways. PMID:26596641

  9. Three-dimensional magnetic cloak working from d.c. to 250 kHz

    PubMed Central

    Zhu, Jianfei; Jiang, Wei; Liu, Yichao; Yin, Ge; Yuan, Jun; He, Sailing; Ma, Yungui

    2015-01-01

    Invisible cloaking is one of the major outcomes of the metamaterial research, but the practical potential, in particular for high frequencies (for example, microwave to visible light), is fatally challenged by the complex material properties they usually demand. On the other hand, it will be advantageous and also technologically instrumental to design cloaking devices for applications at low frequencies where electromagnetic components are favourably uncoupled. In this work, we vastly develop the bilayer approach to create a three-dimensional magnetic cloak able to work in both static and dynamic fields. Under the quasi-static approximation, we demonstrate a perfect magnetic cloaking device with a large frequency band from 0 to 250 kHz. The practical potential of our device is experimentally verified by using a commercial metal detector, which may lead us to having a real cloaking application where the dynamic magnetic field can be manipulated in desired ways. PMID:26596641

  10. Three-dimensional magnetic cloak working from d.c. to 250 kHz

    NASA Astrophysics Data System (ADS)

    Zhu, Jianfei; Jiang, Wei; Liu, Yichao; Yin, Ge; Yuan, Jun; He, Sailing; Ma, Yungui

    2015-11-01

    Invisible cloaking is one of the major outcomes of the metamaterial research, but the practical potential, in particular for high frequencies (for example, microwave to visible light), is fatally challenged by the complex material properties they usually demand. On the other hand, it will be advantageous and also technologically instrumental to design cloaking devices for applications at low frequencies where electromagnetic components are favourably uncoupled. In this work, we vastly develop the bilayer approach to create a three-dimensional magnetic cloak able to work in both static and dynamic fields. Under the quasi-static approximation, we demonstrate a perfect magnetic cloaking device with a large frequency band from 0 to 250 kHz. The practical potential of our device is experimentally verified by using a commercial metal detector, which may lead us to having a real cloaking application where the dynamic magnetic field can be manipulated in desired ways.

  11. 0.26-Hz-linewidth ultrastable lasers at 1557 nm

    PubMed Central

    Wu, Lifei; Jiang, Yanyi; Ma, Chaoqun; Qi, Wen; Yu, Hongfu; Bi, Zhiyi; Ma, Longsheng

    2016-01-01

    Narrow-linewidth ultrastable lasers at 1.5 μm are essential in many applications such as coherent transfer of light through fiber and precision spectroscopy. Those applications all rely on the ultimate performance of the lasers. Here we demonstrate two ultrastable lasers at 1557 nm with a most probable linewidth of 0.26 Hz by independently frequency-stabilizing to the resonance of 10-cm-long ultrastable Fabry-Pérot cavities at room temperature. The fractional frequency instability of each laser system is nearly 8 × 10−16 at 1–30 s averaging time, approaching the thermal noise limit of the reference cavities. A remarkable frequency instability of 1 × 10−15 is achieved on the long time scale of 100–4000 s. PMID:27117356

  12. 0.26-Hz-linewidth ultrastable lasers at 1557 nm.

    PubMed

    Wu, Lifei; Jiang, Yanyi; Ma, Chaoqun; Qi, Wen; Yu, Hongfu; Bi, Zhiyi; Ma, Longsheng

    2016-01-01

    Narrow-linewidth ultrastable lasers at 1.5 μm are essential in many applications such as coherent transfer of light through fiber and precision spectroscopy. Those applications all rely on the ultimate performance of the lasers. Here we demonstrate two ultrastable lasers at 1557 nm with a most probable linewidth of 0.26 Hz by independently frequency-stabilizing to the resonance of 10-cm-long ultrastable Fabry-Pérot cavities at room temperature. The fractional frequency instability of each laser system is nearly 8 × 10(-16) at 1-30 s averaging time, approaching the thermal noise limit of the reference cavities. A remarkable frequency instability of 1 × 10(-15) is achieved on the long time scale of 100-4000 s. PMID:27117356

  13. 0.26-Hz-linewidth ultrastable lasers at 1557 nm

    NASA Astrophysics Data System (ADS)

    Wu, Lifei; Jiang, Yanyi; Ma, Chaoqun; Qi, Wen; Yu, Hongfu; Bi, Zhiyi; Ma, Longsheng

    2016-04-01

    Narrow-linewidth ultrastable lasers at 1.5 μm are essential in many applications such as coherent transfer of light through fiber and precision spectroscopy. Those applications all rely on the ultimate performance of the lasers. Here we demonstrate two ultrastable lasers at 1557 nm with a most probable linewidth of 0.26 Hz by independently frequency-stabilizing to the resonance of 10-cm-long ultrastable Fabry-Pérot cavities at room temperature. The fractional frequency instability of each laser system is nearly 8 × 10‑16 at 1–30 s averaging time, approaching the thermal noise limit of the reference cavities. A remarkable frequency instability of 1 × 10‑15 is achieved on the long time scale of 100–4000 s.

  14. The effect of climatic conditions on exercise-induced bronchoconstriction in 10-12 year old students.

    PubMed

    Marefati, Hamid; Vizvari, Exir; Esmaeilizadeh, Mahdi; Boskabady, Mohammad Hossein

    2016-07-01

    Exercise-induced asthma is seen following vigorous or prolonged exercise or physical exertion. It has been suggested that climatic conditions have an influence on exercise-induced asthma. Therefore, the aim of the present study was to examine the effect of two climatic conditions on exercise-induced deterioration of pulmonary function tests in 10-12 year old students. Two hundred and fifty six students were randomly chosen from two cities namely Kerman and Gorgan (128 subjects in each who were equally from both cities) including 62 girls and 66 boys of 10-12 years old. A questionnaire was used to obtain demographic information and to identify the prevalence of asthma symptoms. Each subject performed a seven-minute free run exercise with maximum effort and sufficient motivation until they reached 70-75% heart rate. Pulmonary function tests (PFT) including, forced vital capacity (FVC), forced expiratory volume in one second (FEV1), peak expiratory flow (PEF), and maximum expiratory flow at 50% of vital capacity (MEF50) were measured before, at the beginning, and 7 and 20 min after physical activity. The prevalence of both asthma (28.12%) and exercise-induced asthma (20.31%) in Kerman students was higher than those of Gorgan students (21.09% and 17%, respectively). All PFT values declined 7 and 20 min post-exercise in both groups. Although all baselines PFT in Kerman students were higher than those of Gorgan students, the decline in PFT values in Kerman students was greater than those of Gorgan students. At 20 min post exercise, the decline in FEV1, PEF and MEF50 in Kerman students was significantly higher than those of Gorgan students (p < 0.05 to p < 0.01). The results of the present study showed that prevalence of both asthma and exercise-induced asthma in a city with dry and cool climate such as Kerman was higher than in a city with humid climate such as Gorgan. In addition, the results showed that in a humid climate, post-exercise decline in PFT values was

  15. Thermal Noise Limit in Frequency Stabilization of Lasers with Rigid Cavities

    NASA Technical Reports Server (NTRS)

    Numata, Kenji; Kemery, Amy; Camp, Jordan

    2004-01-01

    We evaluated thermal noise (Brownian motion) in a rigid reference cavity used for frequency stabilization of lasers, based on the mechanical loss of cavity materials and the numerical analysis of the mirror-spacer mechanics with t.he direct application of the fluctuation dissipation theorem. This noise sets a fundamental limit for the frequency stability achieved with a rigid frequency- reference cavity of order 1 Hz/square root Hz(0.01 Hz/square root Hz) at 10 mHz (100 Hz) at room temperature. This level coincides with the world-highest level stabilization results.

  16. Thermal-noise limit in the frequency stabilization of lasers with rigid cavities.

    PubMed

    Numata, Kenji; Kemery, Amy; Camp, Jordan

    2004-12-17

    We evaluate thermal noise (Brownian motion) in a rigid reference cavity used for frequency stabilization of lasers, based on the mechanical loss of cavity materials and the numerical analysis of the mirror-spacer mechanics with the direct application of the fluctuation dissipation theorem. This noise sets a fundamental limit for the frequency stability achieved with a rigid frequency-reference cavity of order 1 Hz/ square root Hz (0.01 Hz/ square root Hz) at 10 mHz (100 Hz) at room temperature. This level coincides with the world-highest level stabilization results. PMID:15697887

  17. Optimizations of ozone generator at low resonance frequency

    NASA Astrophysics Data System (ADS)

    Garamoon, A. A.; Elakshar, F. F.; Elsawah, M.

    2009-11-01

    The effect of the frequency on the different parameters of ozone generation in the dielectric barrier discharge (DBD) has been investigated. It is found that at low frequency, (f0 = 325 Hz), an electric resonance can be obtained in the electric circuit. The onset voltage, at which the ozone starts to build up, was reduced from 3.25 kV at 50 Hz to 1.57 kV at 325 Hz. The efficiency has been increased from nearly zero at 50 Hz to 232.94 g/kW h at 200 Hz under applied voltage of 2.025 kV. in here

  18. Characterization of Hearing Thresholds from 500 to 16,000 Hz in Dentists: A Comparative Study

    PubMed Central

    Gonçalves, Claudia Giglio de Oliveira; Santos, Luciana; Lobato, Diolen; Ribas, Angela; Lacerda, Adriana Bender Moreira; Marques, Jair

    2014-01-01

    Introduction High-level noise exposure in dentists' workplaces may cause damages to the auditory systems. High-frequency audiometry is an important tool in the investigation in the early diagnosis of hearing loss. Objectives To analyze the auditory thresholds at frequencies from 500 to 16,000 Hz of dentists in the city of Curitiba. Methods This historic cohort study retrospectively tested hearing thresholds from 500 to 16,000 Hz with a group of dentists from Curitiba, in the state of Paraná, Brazil. Eighty subjects participated in the study, separated into a dentist group and a control group, with the same age range and gender across groups but with no history of occupational exposure to high levels of sound pressure in the control group. Subjects were tested with conventional audiometry and high-frequency audiometry and answered a questionnaire about exposure to noise. Results Results showed that 81% of dentists did not receive any information regarding noise at university; 6 (15%) dentists had sensorineural hearing impairment; significant differences were observed between the groups only at frequencies of 500 Hz and 1,000, 6,000 and 8,000 Hz in the right ear. There was no significant difference between the groups after analysis of mean hearing thresholds of high frequencies with the average hearing thresholds in conventional frequencies; subjects who had been working as dentists for longer than 10 years had worse tonal hearing thresholds at high frequencies. Conclusions In this study, we observed that dentists are at risk for the development of sensorineural hearing loss especially after 10 years of service. PMID:25992172

  19. Frequency comb swept lasers.

    PubMed

    Tsai, Tsung-Han; Zhou, Chao; Adler, Desmond C; Fujimoto, James G

    2009-11-01

    We demonstrate a frequency comb (FC) swept laser and a frequency comb Fourier domain mode locked (FC-FDML) laser for applications in optical coherence tomography (OCT). The fiber-based FC swept lasers operate at a sweep rate of 1kHz and 120kHz, respectively over a 135nm tuning range centered at 1310nm with average output powers of 50mW. A 25GHz free spectral range frequency comb filter in the swept lasers causes the lasers to generate a series of well defined frequency steps. The narrow bandwidth (0.015nm) of the frequency comb filter enables a approximately -1.2dB sensitivity roll off over approximately 3mm range, compared to conventional swept source and FDML lasers which have -10dB and -5dB roll offs, respectively. Measurements at very long ranges are possible with minimal sensitivity loss, however reflections from outside the principal measurement range of 0-3mm appear aliased back into the principal range. In addition, the frequency comb output from the lasers are equally spaced in frequency (linear in k-space). The filtered laser output can be used to self-clock the OCT interference signal sampling, enabling direct fast Fourier transformation of the fringe signals, without the need for fringe recalibration procedures. The design and operation principles of FC swept lasers are discussed and designs for short cavity lasers for OCT and interferometric measurement applications are proposed.

  20. Acute and subchronic toxicity of 20  kHz and 60  kHz magnetic fields in rats

    PubMed Central

    Oshima, Atsushi; Shibuya, Kazumoto; Mitani, Takashi; Negishi, Tadashi

    2015-01-01

    Abstract Despite increasing use of intermediate frequency (IF) magnetic fields (MFs) in occupational and domestic settings, scientific evidence necessary for health risk assessments of IF MF is insufficient. Male and female Crl:CD(SD) rats (12 per sex per group) were exposed to 20 kHz, 0.20 mT(root mean square, rms) or 60 kHz, 0.10 mT(rms) sinusoidal MFs for 22 h day−1 for 14 days (acute) or 13 weeks (subchronic). Experiments were duplicated for each frequency to ensure outcome reproducibility, and examinations were blinded for quality assurance. All rats survived without significant clinical signs until the end of experiments. Some changes in body weight between the MF‐exposed and control groups were observed over the course of exposure, although the directions of the changes were inconsistent and not statistically significant after subchronic exposure. There were significant differences between MF‐exposed and control groups in some organ weights and parameters in hematology and clinical chemistry, but these were minor in magnitude and not repeated in duplicate experiments. Histopathological findings reflecting toxicity were sporadic. Frequencies of other findings were similar to historic data in this rat strain, and findings had no specific relationship to changes in organ weight or parameters of hematology and clinical chemistry in each animal. The changes observed throughout this study were considered biologically isolated and were attributable to chance associations rather than to MF exposure. The results, in particular the histopathological evidence, indicate an absence of toxicity in IF MF‐exposed rats and do not support the hypothesis that IF MF exposure produces significant toxicity. Copyright © 2015. The Authors. Journal of Applied Toxicology Published by John Wiley & Sons Ltd. PMID:25982482

  1. Absolute frequency measurement of an acetylene stabilized laser using a selected single mode from a femtosecond fiber laser comb.

    PubMed

    Ryu, Han Young; Lee, Sung Hun; Lee, Won Kyu; Moon, Han Seb; Suh, Ho Suhng

    2008-03-01

    We performed an absolute frequency measurement of an acetylene stabilized laser utilizing a femtosecond injection locking technique that can select one component among the fiber laser comb modes. The injection locking scheme has all the fiber configurations. Femtosecond comb lines of 250 MHz spacing based on the fiber femtosecond laser were used for injection locking of a distributed feedback (DFB) laser operating at 1542 nm as a frequency reference. The comb injected DFB laser serves as a selection filter of optical comb modes and an amplifier for amplification of the selected mode. The DFB laser injection locked to the desired comb mode was used to evaluate the frequency stability and absolute frequency measurement of an acetylene stabilized laser. The frequency stability of the acetylene stabilized laser was measured to be 1.1 x 10(-12) for a 1 s averaging time, improving to 6.9 x 10(-14) after 512 s. The absolute frequency of the laser stabilized on the P(16) transition of (13)C(2)H(2) was measured to be 194 369 569 385.7 kHz.

  2. a Thermoacoustically-Driven Pulse Tube Cryocryocooler Operating around 300HZ

    NASA Astrophysics Data System (ADS)

    Yu, G. Y.; Zhu, S. L.; Dai, W.; Luo, E. C.

    2008-03-01

    High frequency operation of the thermoacoustic cryocooler system, i.e. pulse tube cryocooler driven by thermoacoustic engine, leads to reduced size, which is quite attractive to small-scale cryogenic applications. In this work, a no-load coldhead temperature of 77.8 K is achieved on a 292 Hz pulse tube cryocooler driven by a standing-wave thermoacoustic engine with 3.92 MPa helium gas and 1750 W heat input. To improve thermal efficiency, a high frequency thermoacoustic-Stirling heat engine is also built to drive the same pulse tube cryocooler, and a no-load temperature of 109 K was obtained with 4.38 MPa helium gas, 292 Hz working frequency and 400W heating power. Ideas such as tapered resonators, acoustic amplifier tubes and simple thin tubes without reservoir are used to effectively suppress harmonic modes, amplify the acoustic pressure wave available to the pulse tube cryocooler and provide desired acoustic impedance for the pulse tube cryocooler, respectively. Comparison of systems with different thermoacoustic engines is made. Numerical simulations based on the linear thermoacoustic theory have also been done for comparison with experimental results, which shows reasonable agreement.

  3. Reducing the Heat Load on the LCLS 120 Hz RF Gun with RF Pulse Shaping

    SciTech Connect

    Schmerge, J.

    2005-01-31

    The LCLS injector must operate at 120 Hz repetition frequency but to date the maximum operating frequency of an S-band rf gun has been 50 Hz. The high fields desired for the LCLS gun operation limit the repetition frequency due to thermal expansion causing rf detuning and field redistribution. One method of addressing the thermal loading problem is too reduce the power lost on the cavity walls by properly shaping the rf pulse incident on the gun. The idea is to reach the steady state field value in the gun faster than the time constant of the gun would allow when using a flat incident rf pulse. By increasing the incident power by about a factor of three and then decreasing the incident power when the field reaches the desired value in the gun, the field build up time can be decreased by more than a factor of three. Using this technique the heat load is also decreased by more than a factor of three. In addition the rf coupling coefficient can be increased from the typical critically coupled designs to an overcoupled design which also helps reduce the field build up time. Increasing the coupling coefficient from 1 to 2 reduces the heat load by another 25% and still limits the reflected power and coupling hole size to manageable levels.

  4. A four kHz repetition rate compact TEA CO2 laser

    NASA Astrophysics Data System (ADS)

    Zheng, Yijun; Tan, Rongqing

    2013-09-01

    A compact transversely excited atmospheric (TEA) CO2 laser with high repetition-rate was reported. The size of the laser is 380 mm×300 mm×200 mm, and the discharge volume is 12×103 mm3. The laser cavity has a length of 320mm and consists of a totally reflective concave mirror with a radius of curvature of 4 m (Cu metal substrate coated with Au) and a partially reflecting mirror. The ultraviolet preionization makes the discharge even and stable,the output energy can be as high as 28 mJ under the circumstance of free oscillation, and the width of the light pulse is 60ns.To acquire the high wind velocity, a turbocharger is used in the system of the fast-gas flow cycle. When the wind speed is 100m/s, the repetition rate of the transversely excited atmospheric CO2 laser is up to 2 kHz. On this basis, a dual modular structure with two sets of the gas discharge unit is adopted to obtain a higher pulse repetition frequency output. The dual discharge unit composed two sets of electrodes and two sets of turbo fan. Alternate trigger technology is used to make the two sets of discharge module work in turn with repetition frequency of 2 kHz, the discharge interval of two sets of the gas discharge unit can be adjusted continuously from 20 microseconds to 250 microseconds. Under the conditions of maintaining the other parameters constant, the repetition frequency of the laser pulse is up to 4 kHz. The total size of laser with dual modular structure is 380mm×520mm×200mm, and the discharge volume is 24×103 mm3 with the cavity length of 520mm.

  5. A calculable, transportable audio-frequency AC reference standard

    SciTech Connect

    Oldham, N.M.; Hetrick, P.S. ); Zeng, X. )

    1989-04-01

    A transportable ac voltage source is described, in which sinusoidal signals are synthesized digitally in the audio-frequency range. The rms value of the output waveform may be calculated by measuring the dc level of the individual steps used to generate the waveform. The uncertainty of this calculation at the 7-V level is typically less than +-5 ppm from 60 Hz to 2 kHz and less than +-10 ppm from 30 Hz to 15 kHz.

  6. Frequency-Shift Hearing Aid

    NASA Technical Reports Server (NTRS)

    Weinstein, Leonard M.

    1994-01-01

    Proposed hearing aid maps spectrum of speech into band of lower frequencies at which ear remains sensitive. By redirecting normal speech frequencies into frequency band from 100 to 1,500 Hz, hearing aid allows people to understand normal conversation, including telephone calls. Principle operation of hearing aid adapted to other uses such as, clearing up noisy telephone or radio communication. In addition, loud-speakers more easily understood in presence of high background noise.

  7. Diode-Pumped Long-Pulse-Length Ho:Tm:YLiF4 Laser at 10 Hz

    NASA Technical Reports Server (NTRS)

    Jani, Mahendra G.; Naranjo, Felipe L.; Barnes, Norman P.; Murray, Keith E.; Lockard, George E.

    1995-01-01

    An optical efficiency of 0.052 under normal mode operation for diode-pumped Ho:Tm:YLiF4 at a pulse repetition frequency of 10 Hz has been achieved. Laser output energy of 30 mJ in single Q-switched pulses with 600-ns pulse length were obtained for an input energy of 3 J. A diffusion-bonded birefringent laser rod consisting of Ho:Tm-doped and undoped pieces of YLF was utilized for 10-Hz operation.

  8. Syllabic (~2-5 Hz) and fluctuation (~1-10 Hz) ranges in speech and auditory processing

    PubMed Central

    Edwards, Erik; Chang, Edward F.

    2013-01-01

    Given recent interest in syllabic rates (~2-5 Hz) for speech processing, we review the perception of “fluctuation” range (~1-10 Hz) modulations during listening to speech and technical auditory stimuli (AM and FM tones and noises, and ripple sounds). We find evidence that the temporal modulation transfer function (TMTF) of human auditory perception is not simply low-pass in nature, but rather exhibits a peak in sensitivity in the syllabic range (~2-5 Hz). We also address human and animal neurophysiological evidence, and argue that this bandpass tuning arises at the thalamocortical level and is more associated with non-primary regions than primary regions of cortex. The bandpass rather than low-pass TMTF has implications for modeling auditory central physiology and speech processing: this implicates temporal contrast rather than simple temporal integration, with contrast enhancement for dynamic stimuli in the fluctuation range. PMID:24035819

  9. Search for a stochastic gravitational wave background at 1-5 Hz with a torsion-bar antenna

    NASA Astrophysics Data System (ADS)

    Kuwahara, Yuya; Shoda, Ayaka; Eda, Kazunari; Ando, Masaki

    2016-08-01

    We set the first upper limit on the stochastic gravitational wave (GW) background in the frequency range of 1-5 Hz using a torsion-bar antenna (TOBA). A TOBA is a GW detector designed for the detection of low frequency GWs on the ground, with two orthogonal test masses rotated by the incident GWs. We performed a 24-hour observation run using the TOBA and set upper limits, based on frequentist statistics and Bayesian statistics. The most stringent values are Ωgwh02≤6.0 ×1 018 (frequentist) and Ωgwh02≤1.2 ×1 020 (Bayesian) both at 2.58 Hz, where h0 is the Hubble constant in units of 100 km /s /Mpc and Ωgw is the GW energy density per logarithmic frequency interval in units of the closure density.

  10. Evaluation of the economic burden of Herpes Zoster (HZ) infection

    PubMed Central

    Panatto, Donatella; Bragazzi, Nicola Luigi; Rizzitelli, Emanuela; Bonanni, Paolo; Boccalini, Sara; Icardi, Giancarlo; Gasparini, Roberto; Amicizia, Daniela

    2014-01-01

    The main objective of this systematic review was to evaluate the economic burden of Herpes Zoster (HZ) infection. The review was conducted in accordance with the standards of the “Preferred Reporting Items for Systematic Reviews and Meta-Analyses” guidelines. The following databases were accessed: ISI/Web of Knowledge (WoS), MEDLINE/PubMed, Scopus, ProQuest, the Cochrane Library and EconLit. Specific literature on health economics was also manually inspected. Thirty-three studies were included. The quality of the studies assessed in accordance with the Consolidated Health Economic Evaluation Reporting Standards checklist was good. All studies evaluated direct costs, apart from one which dealt only with indirect costs. Indirect costs were evaluated by 12 studies. The economic burden of HZ has increased over time. HZ management and drug prescriptions generate the highest direct costs. While increasing age, co-morbidities and drug treatment were found to predict higher direct costs, being employed was correlated with higher indirect costs, and thus with the onset age of the disease. Despite some differences among the selected studies, particularly with regard to indirect costs, all concur that HZ is a widespread disease which has a heavy social and economic burden. PMID:25483704

  11. Evaluation of the economic burden of Herpes Zoster (HZ) infection.

    PubMed

    Panatto, Donatella; Bragazzi, Nicola Luigi; Rizzitelli, Emanuela; Bonanni, Paolo; Boccalini, Sara; Icardi, Giancarlo; Gasparini, Roberto; Amicizia, Daniela

    2015-01-01

    The main objective of this systematic review was to evaluate the economic burden of Herpes Zoster (HZ) infection.   The review was conducted in accordance with the standards of the "Preferred Reporting Items for Systematic Reviews and Meta-Analyses" guidelines. The following databases were accessed: ISI/Web of Knowledge (WoS), MEDLINE/PubMed, Scopus, ProQuest, the Cochrane Library and EconLit. Specific literature on health economics was also manually inspected. Thirty-three studies were included. The quality of the studies assessed in accordance with the Consolidated Health Economic Evaluation Reporting Standards checklist was good. All studies evaluated direct costs, apart from one which dealt only with indirect costs. Indirect costs were evaluated by 12 studies. The economic burden of HZ has increased over time. HZ management and drug prescriptions generate the highest direct costs. While increasing age, co-morbidities and drug treatment were found to predict higher direct costs, being employed was correlated with higher indirect costs, and thus with the onset age of the disease. Despite some differences among the selected studies, particularly with regard to indirect costs, all concur that HZ is a widespread disease which has a heavy social and economic burden.

  12. Cochlear nonlinearity between 500 and 8000 Hz in listeners with impaired hearing

    NASA Astrophysics Data System (ADS)

    Lopez-Poveda, Enrique A.; Plack, Christopher J.; Meddis, Ray; Blanco, Jose L.

    2003-10-01

    Cochlear nonlinearity was estimated in listeners with impaired hearing using a forward-masking method. For a fixed low-level probe, the masker level required to mask the probe was measured as a function of the masker-probe interval, to produce a temporal masking curve (TMC). TMCs were measured for probe frequencies from 500 to 8000 Hz, and for masker frequencies from 0.5 to 1.6 times the probe frequency. Unlike what happens for normal-hearing (NH) listeners [Lopez-Poveda et al., J. Acoust. Soc. Am. 113, 951-960 (2003)], TMCs for on-frequency maskers sometimes show a single slope, suggesting linear responses for tones at CF. Sometimes, however, two distinct slopes are visible, suggesting remaining compression. Both patterns are uncorrelated with the absolute threshold and are consistent with selective damage to outer or inner hair cells (IHC), respectively. Remarkably, the slope of the TMCs for very low-frequency maskers is shallower for the impaired ears than for normal ones. This result implies that for NH listeners, the slope of the TMCs for very low-frequency maskers reflects some kind of compression, even at high CFs. It is discussed that this compression is likely to occur at the IHC rather than at the basilar membrane. [Work supported by FIS PI020343, G03/203, and Oticon Spain.

  13. Evolution of CPMAS under fast magic-angle-spinning at 100 kHz and beyond.

    PubMed

    Wickramasinghe, Ayesha; Wang, Songlin; Matsuda, Isamu; Nishiyama, Yusuke; Nemoto, Takahiro; Endo, Yuki; Ishii, Yoshitaka

    2015-11-01

    This article describes recent trends of high-field solid-state NMR (SSNMR) experiments for small organic molecules and biomolecules using (13)C and (15)N CPMAS under ultra-fast MAS at a spinning speed (νR) of 80-100kHz. First, we illustrate major differences between a modern low-power RF scheme using UFMAS in an ultra-high field and a traditional CPMAS scheme using a moderate sample spinning in a lower field. Features and sensitivity advantage of a low-power RF scheme using UFMAS and a small sample coil are summarized for CPMAS-based experiments. Our 1D (13)C CPMAS experiments for uniformly (13)C- and (15)N-labeled alanine demonstrated that the sensitivity per given sample amount obtained at νR of 100kHz and a (1)H NMR frequency (νH) of 750.1MHz is ~10 fold higher than that of a traditional CPMAS experiment obtained at νR of 20kHz and νH of 400.2MHz. A comparison of different (1)H-decoupling schemes in CPMAS at νR of 100kHz for the same sample demonstrated that low-power WALTZ-16 decoupling unexpectedly displayed superior performance over traditional low-power schemes designed for SSNMR such as TPPM and XiX in a range of decoupling field strengths of 5-20kHz. Excellent (1)H decoupling performance of WALTZ-16 was confirmed on a protein microcrystal sample of GB1 at νR of 80kHz. We also discuss the feasibility of a SSNMR microanalysis of a GB1 protein sample in a scale of 1nmol to 80nmol by (1)H-detected 2D (15)N/(1)H SSNMR by a synergetic use of a high field, a low-power RF scheme, a paramagnetic-assisted condensed data collection (PACC), and UFMAS.

  14. Extended frequency turbofan model

    NASA Technical Reports Server (NTRS)

    Mason, J. R.; Park, J. W.; Jaekel, R. F.

    1980-01-01

    The fan model was developed using two dimensional modeling techniques to add dynamic radial coupling between the core stream and the bypass stream of the fan. When incorporated into a complete TF-30 engine simulation, the fan model greatly improved compression system frequency response to planar inlet pressure disturbances up to 100 Hz. The improved simulation also matched engine stability limits at 15 Hz, whereas the one dimensional fan model required twice the inlet pressure amplitude to stall the simulation. With verification of the two dimensional fan model, this program formulated a high frequency F-100(3) engine simulation using row by row compression system characteristics. In addition to the F-100(3) remote splitter fan, the program modified the model fan characteristics to simulate a proximate splitter version of the F-100(3) engine.

  15. PROCEEDINGS OF RIKEN BNL RESEARCH CENTER WORKSHOP, VOLUME 77, RBRC SCIENTIFIC REVIEW COMMITTEE MEETING, OCTOBER 10-12, 2005

    SciTech Connect

    SAMIOS, N.P.

    2005-10-10

    The eighth evaluation of the RIKEN BNL Research Center (RBRC) took place on October 10-12, 2005, at Brookhaven National Laboratory. The members of the Scientific Review Committee (SRC) were Dr. Jean-Paul Blaizot, Professor Makoto Kobayashi, Dr. Akira Masaike, Professor Charles Young Prescott (Chair), Professor Stephen Sharpe (absent), and Professor Jack Sandweiss. We are grateful to Professor Akira Ukawa who was appointed to the SRC to cover Professor Sharpe's area of expertise. In addition to reviewing this year's program, the committee, augmented by Professor Kozi Nakai, evaluated the RBRC proposal for a five-year extension of the RIKEN BNL Collaboration MOU beyond 2007. Dr. Koji Kaya, Director of the Discovery Research Institute, RIKEN, Japan, presided over the session on the extension proposal. In order to illustrate the breadth and scope of the RBRC program, each member of the Center made a presentation on higher research efforts. In addition, a special session was held in connection with the RBRC QCDSP and QCDOC supercomputers. Professor Norman H. Christ, a collaborator from Columbia University, gave a presentation on the progress and status of the project, and Professor Frithjof Karsch of BNL presented the first physics results from QCDOC. Although the main purpose of this review is a report to RIKEN Management (Dr. Ryoji Noyori, RIKEN President) on the health, scientific value, management and future prospects of the Center, the RBRC management felt that a compendium of the scientific presentations are of sufficient quality and interest that they warrant a wider distribution. Therefore we have made this compilation and present it to the community for its information and enlightenment.

  16. Frequency Responses of Rat Retinal Ganglion Cells

    PubMed Central

    Cloherty, Shaun L.; Hung, Yu-Shan; Kameneva, Tatiana; Ibbotson, Michael R.

    2016-01-01

    There are 15–20 different types of retinal ganglion cells (RGC) in the mammalian retina, each encoding different aspects of the visual scene. The mechanism by which post-synaptic signals from the retinal network generate spikes is determined by each cell’s intrinsic electrical properties. Here we investigate the frequency responses of morphologically identified rat RGCs using intracellular injection of sinusoidal current waveforms, to assess their intrinsic capabilities with minimal contributions from the retinal network. Recorded cells were classified according to their morphological characteristics (A, B, C or D-type) and their stratification (inner (i), outer (o) or bistratified) in the inner plexiform layer (IPL). Most cell types had low- or band-pass frequency responses. A2, C1 and C4o cells were band-pass with peaks of 15–30 Hz and low-pass cutoffs above 56 Hz (A2 cells) and ~42 Hz (C1 and C4o cells). A1 and C2i/o cells were low-pass with peaks of 10–15 Hz (cutoffs 19–25 Hz). Bistratified D1 and D2 cells were also low-pass with peaks of 5–10 Hz (cutoffs ~16 Hz). The least responsive cells were the B2 and C3 types (peaks: 2–5 Hz, cutoffs: 8–11 Hz). We found no difference between cells stratifying in the inner and outer IPL (i.e., ON and OFF cells) or between cells with large and small somas or dendritic fields. Intrinsic physiological properties (input resistance, spike width and sag) had little impact on frequency response at low frequencies, but account for 30–40% of response variability at frequencies >30 Hz. PMID:27341669

  17. Hemodynamic responses can modulate the brain oscillations in low frequency

    NASA Astrophysics Data System (ADS)

    Lu, Feng-Mei; Wang, Yi-Feng; Yuan, Zhen

    2016-03-01

    Previous studies have showed that the steady-state responses were able to be used as an effective index for modulating the neural oscillations in the high frequency ranges (> 1 Hz). However, the neural oscillations in low frequency ranges (<1 Hz) remain unknown. In this study, a series of fNIRS experimental tests were conducted to validate if the low frequency bands (0.1 Hz - 0.8 Hz) steady-state hemoglobin responses (SSHbRs) could be evoked and modulate the neural oscillation during a serial reaction time (SRT) task.

  18. A recirculating delayed self-heterodyne method using a Mach-Zehnder modulator for kHz-linewidth measurement

    NASA Astrophysics Data System (ADS)

    Deng, Shuo; Li, Min; Gao, Hongyun; Dai, Yawen

    2016-09-01

    A laser linewidth measurement method which uses a Mach-Zehnder electro-optic modulator (MZM) is proposed in a loss-compensated recirculating delayed self-heterodyne interferometer (LC-RDSHI). Compared with the traditional acousto-optic modulator (AOM), the electro-optic modulator has the merits of broader bandwidth, lower insertion loss, higher extinction ratio and thus, a wider application. A theoretical analysis shows that the power spectrum curve of the novel measurement system is a Lorentzian line, which fits well with experiment. The linewidth is measured to be 137 ± 7 kHz at a frequency shift of 4 GHz. Measurement of a distributed feedback Bragg (DFB) laser has manifested that the linewidth broadens from 98.5 kHz to 137.4 kHz as the operating temperature changes by 16 °C. This work will allow investigation of narrow linewidth semiconductor and fiber laser stability.

  19. Evaluation of potential health effects of 10 kHz magnetic fields: a rodent reproductive study.

    PubMed

    Dawson, B V; Robertson, I G; Wilson, W R; Zwi, L J; Boys, J T; Green, A W

    1998-01-01

    New technology involving the use of high-frequency inductive power distribution (HID) has recently been developed for use in materials handling and personnel transfer. Sinusoidal magnetic fields at a frequency of 10 kHz with field intensities of approximately 0.2 mT are generated directly between the current-carrying coils of this equipment. Effects of 10 kHz magnetic fields on cell division, migration, and differentiation have never been previously investigated. To evaluate potential effects on these parameters, a rodent reproductive study was undertaken using Wistar rats. Exposures were at 0.095, 0.24, and 0.95 mT with a background exposure of 5-10 microT. Three sets of parental rats were exposed continuously for 20-23.5 h/day to the fields: maternal rats during gestation, paternal rats for at least 45 days prior to mating and maternal rats 1 month prior to mating. Exposure phases thus covered spermatogenesis, maturation of the ovum and ovulation, fertilization, implantation, embryogenesis, organogenesis, and maturation of the fetus immediately prior to parturition. In all experiments pregnancy outcome was assessed. These studies failed to demonstrate any reproductive toxicity resulting from maternal or fetal exposure during gestation or following paternal or maternal exposure for several weeks prior to mating. No quantitative or qualitative effects on spermatogenesis occurred after exposure, and no effects on the estrous cycle or ovulation could be demonstrably linked to the 10 kHz magnetic field exposure at 0.095, 0.25, or 0.95 mT. Where possible, parental clinical chemistry and hematology were also examined. As in mouse toxicology studies previously reported, minor differences were observed between control and treated groups. These were regarded as statistically, but not biologically, significant and could not categorically be attributed to magnetic field exposure.

  20. 47 CFR 18.303 - Prohibited frequency bands.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false Prohibited frequency bands. 18.303 Section 18.303 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL INDUSTRIAL, SCIENTIFIC, AND MEDICAL... following safety, search and rescue frequency bands is prohibited: 490-510 kHz, 2170-2194 kHz, 8354-8374...

  1. 47 CFR 18.303 - Prohibited frequency bands.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 1 2011-10-01 2011-10-01 false Prohibited frequency bands. 18.303 Section 18.303 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL INDUSTRIAL, SCIENTIFIC, AND MEDICAL... following safety, search and rescue frequency bands is prohibited: 490-510 kHz, 2170-2194 kHz, 8354-8374...

  2. Space station 20-kHz power management and distribution system

    NASA Technical Reports Server (NTRS)

    Hansen, I. G.; Sundberg, G. R.

    1986-01-01

    During the conceptual design phase a 20-kHz power distribution system was selected as the reference for the space station. The system is single-phase 400 VRMS, with a sinusoidal wave form. The initial user power level will be 75 kW with growth to 300 kW. The high-frequency system selection was based upon considerations of efficiency, weight, safety, ease of control, interface with computers, and ease of paralleling for growth. Each of these aspects will be discussed as well as the associated trade-offs involved. An advanced development program has been instituted to accelerate the maturation of the high-frequency system. Some technical aspects of the advanced development will be discussed.

  3. Space Station 20-kHz power management and distribution system

    NASA Technical Reports Server (NTRS)

    Hansen, Irving G.; Sundberg, Gale R.

    1986-01-01

    During the conceptual design phase a 20-kHz power distribution system was selected as the reference for the Space Station. The system is single-phase 400 VRMS, with a sinusoidal wave form. The initial user power level will be 75 kW with growth to 300 kW. The high-frequency system selection was based upon considerations of efficiency, weight, safety, ease of control, interface with computers, and ease of paralleling for growth. Each of these aspects will be discussed as well as the associated trade-offs involved. An advanced development program has been instituted to accelerate the maturation of the high-frequency system. Some technical aspects of the advanced development will be discussed.

  4. The gravitational resolving power of global seismic networks in the 0.1-10 Hz band

    NASA Astrophysics Data System (ADS)

    Mulargia, Francesco; Kamenshchik, Alexander

    2016-04-01

    Among the first attempts to detect gravitational waves, the seismic approach pre-dates the digital era. Major advances in computational power, seismic instrumentation and in the knowledge of seismic noise suggest to reappraise its potential. Using the whole earth as a detector, with the thousands of digital seismometers of seismic global networks as a single phased array, more than two decades of continuous seismic noise data are available and can be readily sifted at the only cost of (a pretty gigantic) computation. Using a subset of data, we show that absolute strains h ≲10-17 on burst gravitational pulses and h ≲10-21 on periodic signals may be feasibly resolved in the frequency range 0.1-10 Hz, only marginally covered by current advanced LIGO and future eLISA. However, theoretical predictions for the largest cosmic gravitational emissions at these frequencies are a few orders of magnitude lower.

  5. Noise measurements in a 2-hole radio frequency SQUID at liquid nitrogen temperature

    SciTech Connect

    Harrop, S.P.; Colclough, M.S.; Gough, C.E.; Keene, M.N.; Muirhead, C.M.

    1989-03-01

    The authors report measurements of the noise in a 2-hole r.f. SQUID fabricated from bulk YBCO by an erosion technique in the frequency range 30mHz to 1kHz. Above 100Hz the noise is essentially white with an rms value of 5.10/sup -4/..cap alpha..o/..sqrt..Hz and is dominated by noise from the electronics. Below 10Hz the noise power rises as l/f/sup 0.9/.

  6. A broadband, capacitive, surface-micromachined, omnidirectional microphone with more than 200 kHz bandwidth.

    PubMed

    Kuntzman, Michael L; Hall, Neal A

    2014-06-01

    A surface micromachined microphone is presented with 230 kHz bandwidth. The structure uses a 2.25 μm thick, 315 μm radius polysilicon diaphragm suspended above an 11 μm gap to form a variable parallel-plate capacitance. The back cavity of the microphone consists of the 11 μm thick air volume immediately behind the moving diaphragm and also an extended lateral cavity with a radius of 504 μm. The dynamic frequency response of the sensor in response to electrostatic signals is presented using laser Doppler vibrometry and indicates a system compliance of 0.4 nm/Pa in the flat-band of the response. The sensor is configured for acoustic signal detection using a charge amplifier, and signal-to-noise ratio measurements and simulations are presented. A resolution of 0.80 mPa/√Hz (32 dB sound pressure level in a 1 Hz bin) is achieved in the flat-band portion of the response extending from 10 kHz to 230 kHz. The proposed sensor design is motivated by defense and intelligence gathering applications that require broadband, airborne signal detection.

  7. Instrumental Conditioning of Human Sensorimotor Rhythm (12–15 Hz) and Its Impact on Sleep as Well as Declarative Learning

    PubMed Central

    Hoedlmoser, Kerstin; Pecherstorfer, Thomas; Gruber, Georg; Anderer, Peter; Doppelmayr, Michael; Klimesch, Wolfgang; Schabus, Manuel

    2008-01-01

    Study Objectives: To test whether instrumental conditioning of sensorimotor rhythm (SMR; 12–15 Hz) has an impact on sleep parameters as well as declarative memory performance in humans. Design: Randomized, parallel group design Setting: 10 instrumental conditioning sessions, pre- and posttreatment investigation including sleep evaluations Participants: 27 healthy subjects (13 male) Interventions: SMR-conditioning (experimental group) or randomized-frequency conditioning (control group); declarative memory task before and after a 90-min nap Measurement and Results: The experimental group was trained to enhance the amplitude of their SMR-frequency range, whereas the control group participated in a randomized-frequency conditioning program (i.e., every session a different 3-Hz frequency bin between 7 and 20 Hz). During pre- and posttreatment the subjects had to attend the sleep laboratory to take a 90-min nap (2:00–3:30 pm) and to perform a declarative memory task before and after sleep. The experimental design was successful in conditioning an increase in relative 12–15 Hz amplitude within 10 sessions (d = 0.7). Increased SMR activity was also expressed during subsequent sleep by eliciting positive changes in different sleep parameters (sleep spindle number [d = 0.6], sleep onset latency [d = 0.7]); additionally, this increased 12–15 Hz amplitude was associated with enhancement in retrieval score computed at immediate cued recall (d = 0.9). Conclusion: Relative SMR amplitude increased over 10 instrumental conditioning sessions (in the experimental group only) and this “shaping of one's own brain activity” improved subsequent declarative learning and facilitated the expression of 12–15 Hz spindle oscillations during sleep. Most interestingly, these electrophysiological changes were accompanied by a shortened sleep onset latency. Citation: Hoedlmoser K; Pecherstorfer T; Gruber G; Anderer P; Doppelmayr M; Klimesch W; Schabus M. Instrumental conditioning of

  8. Reduction of dopamine synaptic activity: degradation of 50-kHz ultrasonic vocalization in rats.

    PubMed

    Ciucci, Michelle R; Ahrens, Allison M; Ma, Sean T; Kane, Jacqueline R; Windham, E Blake; Woodlee, Martin T; Schallert, Timothy

    2009-04-01

    Vocal deficits are prevalent and debilitating in Parkinson's disease. These deficits may be related to the initial pathology of the nigrostriatal dopamine neurons and resulting dopamine depletion, which contributes to dysfunction of fine motor control in multiple functions. Although vocalization in animals and humans may differ in many respects, we evaluated complex (50-kHz) ultrasonic mate calls in 2 rat models of Parkinson's disease, including unilateral infusions of 6-hydroxydopamine to the medial forebrain bundle and peripheral administration of a nonakinesia dose of the dopamine antagonist haloperidol. We examined the effects of these treatments on multiple aspects of the acoustic signal. The number of trill-like (frequency modulated) 50-kHz calls was significantly reduced, and appeared to be replaced by simpler (flat) calls. The bandwidth and maximum intensity of simple and frequency-modulated calls were significantly decreased, but call duration was not. Our findings suggest that the nigrostriatal dopamine pathway is involved to some extent in fine sensorimotor function that includes USV production and complexity.

  9. The effect of wind-generated bubbles on sea-surface backscattering at 940 Hz.

    PubMed

    van Vossen, Robbert; Ainslie, Michael A

    2011-11-01

    Reliable predictions of sea-surface backscattering strength are required for sonar performance modeling. These are, however, difficult to obtain as measurements of sea-surface backscattering are not available at small grazing angles relevant to low-frequency active sonar (1-3 kHz). Accurate theoretical predictions of scattering strength require a good understanding of physical mechanisms giving rise to the scattering and the relative importance of these. In this paper, scattering from individual resonant bubbles is introduced as a potential mechanism and a scattering model is derived that incorporates the contribution from these together with that of rough surface scattering. The model results are fitted to Critical Sea Test (CST) measurements at a frequency of 940 Hz, treating the number of large bubbles, parameterized through the spectral slope of the size spectrum for bubbles whose radii exceed 1 mm, as a free parameter. This procedure illustrates that the CST data can be explained by scattering from a small number of large resonant bubbles, indicating that these provide an alternative mechanism to that of scattering from bubble clouds.

  10. Quasi-periodic (~mHz) dayside auroral brightennings associated with high-speed solar wind

    NASA Astrophysics Data System (ADS)

    Liou, K.

    2013-12-01

    It has been reported that dayside auroral pulsations of a few mHz frequency can occur when variations of solar wind dynamic pressure at the same frequency appear. Magnetospheric compression/decompression is attributed to the auroral pulsations. Here we report another type of dayside auroral pulsations not associated with solar wind dynamic pressure changes by using global auroral images acquired from the Ultraviolet Imager (UVI) on board the Polar satellite. From one periodic (~2 - 8 mHz) auroral event that occurred on February 8, 2000, it is found that the auroral enhancements covered most of the day (~05 - 16 MLT) sector and did not show a latitudinal dependence. Based on in situ particle data from DMSP SSJ/4, the brightennings were associated mainly with enhanced particle precipitations from the central plasma sheet (i.e., diffuse aurora). There was no geomagnetic pulsation on the ground and in the dawn sector of the magnetosheath as indicated by the Geotail measurements. While the auroral pulsations occurred during high solar wind speed (> 600 km/s), they commenced when the interplanetary magnetic field turned northward, suggesting the Kelvin-Helmholtz instability being a source of the pulsations. We will present detail analysis results and discuss other possible mechanisms in the context of current theories.

  11. Fast Activity Evoked by Intracranial 50 Hz Electrical Stimulation as a Marker of the Epileptogenic Zone.

    PubMed

    Bellistri, Elisa; Sartori, Ivana; Pelliccia, Veronica; Francione, Stefano; Cardinale, Francesco; de Curtis, Marco; Gnatkovsky, Vadym

    2015-08-01

    Epilepsy is a disease characterized by aberrant connections between brain areas. The altered activity patterns generated by epileptic networks can be analyzed with intracerebral electrodes during pre-surgical stereo-electroencephalographic (EEG) monitoring in patients candidate to epilepsy surgery. The responses to high frequency stimulation (HFS) at 50 Hz performed for diagnostic purposes during SEEG were analyzed with a new algorithm, to evaluate signal parameters that are masked to visual inspection and to define the boundaries of the epileptogenic network. The analysis was focused on 60-80 Hz activity that represented the largest frequency component evoked by HFS. The distribution of HFS-evoked fast activity across all (up to 162) recording contacts allowed to define different clusters of contacts that retrospectively correlated to the epileptogenic zone identified by the clinicians on the basis of traditional visual analysis. The study demonstrates that computer-assisted analysis of HFS-evoked activities may contribute to the definition of the epileptogenic network on intracranial recordings performed in a pre-surgical setting.

  12. 35 Hz shape memory alloy actuator with bending-twisting mode

    PubMed Central

    Song, Sung-Hyuk; Lee, Jang-Yeob; Rodrigue, Hugo; Choi, Ik-Seong; Kang, Yeon June; Ahn, Sung-Hoon

    2016-01-01

    Shape Memory Alloy (SMA) materials are widely used as an actuating source for bending actuators due to their high power density. However, due to the slow actuation speed of SMAs, there are limitations in their range of possible applications. This paper proposes a smart soft composite (SSC) actuator capable of fast bending actuation with large deformations. To increase the actuation speed of SMA actuator, multiple thin SMA wires are used to increase the heat dissipation for faster cooling. The actuation characteristics of the actuator at different frequencies are measured with different actuator lengths and results show that resonance can be used to realize large deformations up to 35 Hz. The actuation characteristics of the actuator can be modified by changing the design of the layered reinforcement structure embedded in the actuator, thus the natural frequency and length of an actuator can be optimized for a specific actuation speed. A model is used to compare with the experimental results of actuators with different layered reinforcement structure designs. Also, a bend-twist coupled motion using an anisotropic layered reinforcement structure at a speed of 10 Hz is also realized. By increasing their range of actuation characteristics, the proposed actuator extends the range of application of SMA bending actuators. PMID:26892438

  13. Multi-mJ, kHz, ps deep-ultraviolet source.

    PubMed

    Chang, Chun-Lin; Krogen, Peter; Liang, Houkun; Stein, Gregory J; Moses, Jeffrey; Lai, Chien-Jen; Siqueira, Jonathas P; Zapata, Luis E; Kärtner, Franz X; Hong, Kyung-Han

    2015-02-15

    We demonstrate a 0.56-GW, 1-kHz, 4.2-ps, 2.74-mJ deep-ultraviolet (DUV) laser at ∼257.7  nm with a beam propagation factor (M2) of ∼2.54 from a frequency-quadrupled cryogenic multi-stage Yb-doped chirped-pulse amplifier. The frequency quadrupling is achieved using LiB3O5 and β-BaB2O4 crystals for near-infrared (NIR)-to-green and green-to-DUV conversion, respectively. An overall NIR-to-DUV efficiency of ∼10% has been achieved, which is currently limited by the thermal-induced phase mismatching and the DUV-induced degradation of transmittance. To the best of our knowledge, this is the highest peak-power picosecond DUV source from a diode-pumped solid-state laser operating at kHz repetition rates. PMID:25680176

  14. The 67 Hz Feature in the Black Hole Candidate GRS 1915+105 as a Possible Diskoseismic Mode

    NASA Technical Reports Server (NTRS)

    Nowak, Michael A.; Wagoner, Robert V.; Begelman, Mitchell C.; Lehr, Dana E.

    1997-01-01

    The Rossi X-Ray Timing Explorer has made feasible for the first time the search for high-frequency (greater than or equal to 100 Hz) periodic features in Black Hole Candidate (BHC) systems. Such a feature, with a 67 Hz frequency, recently has been discovered in the BHC GRS 1915+105 (Morgan, Remillard, & Greiner). This feature is weak (rms variability approx. 0.3%-1.6%), stable in frequency (to within approx. 2 Hz) despite appreciable luminosity fluctuations, and narrow (quality factor Q approx. 20). Several of these properties are what one expects for a 'diskoseismic' g-mode in an accretion disk about a 10.6 M(solar mass) (nonrotating) to 36.3 M(solar mass) (maximally rotating) black hole (if we are observing the fundamental-mode frequency). We explore this possibility by considering the expected luminosity modulation, as well as possible excitation and growth mechanisms-including turbulent excitation, damping, and 'negative' radiation damping. We conclude that a diskoseismic interpretation of the observations is viable.

  15. Molecular Spectroscopy in Hollow-Core Photonic Crystal Fiber at the 10 kHz Level

    NASA Astrophysics Data System (ADS)

    Wang, Chenchen; Knabe, Kevin; Wu, Shun; Lim, Jinkang; Tillman, Karl; Washburn, Brian; Corwin, Kristan; Wheeler, Natalie; Couny, Francois; Benabid, Fetah

    2010-03-01

    High-accuracy spectroscopy in hollow-core photonic crystal fiber (HC-PCF) is desirable for many applications, including frequency references and trace gas analysis. We demonstrate the narrowest sub-Doppler linewidths attained in HC-PCF using large-core kagome structured fiber. Such fibers can yield highly accurate frequency measurements that are about two orders of magnitude higher than previously reported. A fiber laser is locked to the ^12C2H2 ν1+ν3 P(13) transition inside kagome fiber, and compared with two optical frequency combs referenced to a GPS-disciplined Rb oscillator. The absolute frequency of the measured line center agrees with those measured in power build-up cavities to within 9.3 kHz (1 σ error). Approaches to further narrow the linewidths and improve systematic errors are investigated. The present system thus combines accuracy approaching that of power build-up cavities with the potential to be compact, robust, and integrated into an all-fiber system for a portable near-infrared frequency reference. Supported by AFOSR FA9950-05-1-0304 and NSF ECS-0449295.

  16. Surface gravity waves and their acoustic signatures, 1-30 Hz, on the mid-Pacific sea floor.

    PubMed

    Farrell, W E; Munk, Walter

    2013-10-01

    In 1999, Duennebier et al. deployed a hydrophone and geophone below the conjugate depth in the abyssal Pacific, midway between Hawaii and California. Real time data were transmitted for 3 yr over an abandoned ATT cable. These data have been analyzed in the frequency band 1 to 30 Hz. Between 1 and 6 Hz, the bottom data are interpreted as acoustic radiation from surface gravity waves, an extension to higher frequencies of a non-linear mechanism proposed by Longuet-Higgins in 1950 to explain microseisms. The inferred surface wave spectrum for wave lengths between 6 m and 17 cm is saturated (wind-independent) and roughly consistent with the traditional Phillips κ(-4) wave number spectrum. Shorter ocean waves have a strong wind dependence and a less steep wave number dependence. Similar features are found in the bottom record between 6 and 30 Hz. But this leads to an enigma: The derived surface spectrum inferred from the Longuet-Higgins mechanism with conventional assumptions for the dispersion relation is associated with mean square slopes that greatly exceed those derived from glitter. Regardless of the generation mechanism, the measured bottom intensities between 10 and 30 Hz are well below minimum noise standards reported in the literature.

  17. The strain in the array is mainly in the plane (waves below ~1 Hz)

    USGS Publications Warehouse

    Gomberg, J.; Pavlis, G.; Bodin, P.

    1999-01-01

    We compare geodetic and single-station methods of measuring dynamic deformations and characterize their causes in the frequency bands 0.5-1.0 Hz and 4.0-8.0 Hz. The geodetic approach utilizes data from small-aperture seismic arrays, applying techniques from geodesy. It requires relatively few assumptions and a priori information. The single-station method uses ground velocities recorded at isolated or single stations and assumes all the deformation is due to plane-wave propagation. It also requires knowledge of the azimuth and horizontal velocity of waves arriving at the recording station. Data employed come from a small-aperture, dense seismic array deployed in Geyokcha, Turkmenistan, and include seismograms recorded by broadband STS2 and short-period L28 sensors. Poor agreement between geodetic and single-station estimates in the 4.0-8.0 Hz passband indicates that the displacement field may vary nonlinearly with distance over distances of ~50 m. STS2 geodetic estimates provide a robust standard in the 0.5-1.0 Hz passband because they appear to be computationally stable and require fewer assumptions than single-station estimates. The agreement between STS2 geodetic estimates and single-station L28 estimates is surprisingly good for the S-wave and early surface waves, suggesting that the single-station analysis should be useful with commonly available data. These results indicate that, in the 0.5 to 1.0 Hz passband, the primary source of dynamic deformation is plane-wave propagation along great-circle source-receiver paths. For later arriving energy, the effects of scattering become important. The local structure beneath the array exerts a strong control on the geometry of the dynamic deformation, implying that it may be difficult to infer source characteristics of modern or paleoearthquakes from indicators of dynamic deformations. However, strong site control also suggests that the dynamic deformations may be predictable, which would be useful for engineering

  18. Upper Limits on a Stochastic Gravitational-Wave Background Using LIGO and Virgo Interferometers at 600-1000 Hz

    NASA Technical Reports Server (NTRS)

    Abadie, J.; Abbott, B. P.; Abbott, R.; Abbott, T. D.; Abernathy, M.; Accadia, T.; Acernese, F.; Adams, C.; Adhikari, R.; Affeldt, C.; Agathos, M.; Agatsuma, K.; Ajith, P.; Allen, B.; Amador Ceron, E.; Amariutei, D.; Anderson, S. B.; Anderson, W. G.; Arai, K.; Arain, M. A.; Araya, M. C.; Aston, S. M.; Blackburn, L.; Cannizzo, J.

    2012-01-01

    A stochastic background of gravitational waves is expected to arise from a superposition of many incoherent sources of gravitational waves, of either cosmological or astrophysical origin. This background is a target for the current generation of ground-based detectors. In this article we present the first joint search for a stochastic background using data from the LIGO and Virgo interferometers. In a frequency band of 600-1000 Hz, we obtained a 95% upper limit on the amplitude of omega(sub GW)(f) = omega(sub 3) (f/900Hz)3, of omega(sub 3) < 0.33, assuming a value of the Hubble parameter of h(sub 100) = 0.72. These new limits are a factor of seven better than the previous best in this frequency band.

  19. [Selective attention in dogs from energy characteristics of neocortical potentials in the 1-220 Hz band].

    PubMed

    Dumenko, V N; Kozlov, M K; Kulikov, M A

    2001-01-01

    The state of selective attention was studied in dogs in the course of instrumental conditioning. During interstimuli intervals, this state was manifested in the state of strained waiting for conditioned stimuli. Electrical activity of different areas in both hemispheres was analyzed using the Fast Fourier Transformation. It was shown that in the process of development of selective attention, the high-frequency EEG components (40-200 Hz) in the motor area of the right hemisphere and the visual and parietal areas of the left hemisphere had a predominant significance over the traditional EEG frequencies of 1-30 Hz. The state of selective attention was characterized by another functional mosaic organization of the neocortical potentials.

  20. A laser-cooled cesium fountain frequency standard and a measurement of the frequency shift due to ultra-cold collisions

    NASA Technical Reports Server (NTRS)

    Gibble, Kurt; Kasapi, Steven; Chu, Steven

    1993-01-01

    A frequency standard based on an atomic fountain of cesium atoms may have an accuracy of 10(exp -16) due to longer interaction times and smaller anticipated systematic errors. All of the known systematic effects that now limit the accuracy of the Cs frequency standard increase either linearly or as some higher power of the atom's velocity. The one systematic frequency shift which is dramatically different is the frequency shift due to the collisions between the laser cooled atoms. At a temperature of a few micro-K, the de Broglie wavelength (lambda(sub deB) = h/p, where h is Planck's constant and p is the momentum of the atom) is much larger than the scale of the interatomic potential. Under these conditions the collision cross sections can be as large as (lambda(sub deB)(sup 2))/Pi and the frequency shift due to these collisions was recently calculated. In our Cs atomic fountain, we laser cooled and trapped 10(exp 10) Cs atoms in 0.4 s. By shifting the frequencies of the laser beams, the atoms were launched upwards at 2.5 m/s and a fraction of the atoms were optically pumped into the F=3 ground state. The unwanted atoms in the F=4 ground state were removed from the fountain with radiation pressure from a laser beam tuned to excite only those atoms. The Cs atoms in the F=3 state traveled ballistically upwards, were excited by the microwave cavity, and then returned back through the same cavity in the atomic fountain configuration. By varying the cold atom density, a density dependent shift of -12.9 +/- 0.7 mHz or -1.4 x 10-12 for an average fountain density of (2.7 +/- 1.5) 10(exp 9) atoms/cm(sup 3) was measured.

  1. Frequencies of Inaudible High-Frequency Sounds Differentially Affect Brain Activity: Positive and Negative Hypersonic Effects

    PubMed Central

    Fukushima, Ariko; Yagi, Reiko; Kawai, Norie; Honda, Manabu; Nishina, Emi; Oohashi, Tsutomu

    2014-01-01

    The hypersonic effect is a phenomenon in which sounds containing significant quantities of non-stationary high-frequency components (HFCs) above the human audible range (max. 20 kHz) activate the midbrain and diencephalon and evoke various physiological, psychological and behavioral responses. Yet important issues remain unverified, especially the relationship existing between the frequency of HFCs and the emergence of the hypersonic effect. In this study, to investigate the relationship between the hypersonic effect and HFC frequencies, we divided an HFC (above 16 kHz) of recorded gamelan music into 12 band components and applied them to subjects along with an audible component (below 16 kHz) to observe changes in the alpha2 frequency component (10–13 Hz) of spontaneous EEGs measured from centro-parieto-occipital regions (Alpha-2 EEG), which we previously reported as an index of the hypersonic effect. Our results showed reciprocal directional changes in Alpha-2 EEGs depending on the frequency of the HFCs presented with audible low-frequency component (LFC). When an HFC above approximately 32 kHz was applied, Alpha-2 EEG increased significantly compared to when only audible sound was applied (positive hypersonic effect), while, when an HFC below approximately 32 kHz was applied, the Alpha-2 EEG decreased (negative hypersonic effect). These findings suggest that the emergence of the hypersonic effect depends on the frequencies of inaudible HFC. PMID:24788141

  2. Frequencies of inaudible high-frequency sounds differentially affect brain activity: positive and negative hypersonic effects.

    PubMed

    Fukushima, Ariko; Yagi, Reiko; Kawai, Norie; Honda, Manabu; Nishina, Emi; Oohashi, Tsutomu

    2014-01-01

    The hypersonic effect is a phenomenon in which sounds containing significant quantities of non-stationary high-frequency components (HFCs) above the human audible range (max. 20 kHz) activate the midbrain and diencephalon and evoke various physiological, psychological and behavioral responses. Yet important issues remain unverified, especially the relationship existing between the frequency of HFCs and the emergence of the hypersonic effect. In this study, to investigate the relationship between the hypersonic effect and HFC frequencies, we divided an HFC (above 16 kHz) of recorded gamelan music into 12 band components and applied them to subjects along with an audible component (below 16 kHz) to observe changes in the alpha2 frequency component (10-13 Hz) of spontaneous EEGs measured from centro-parieto-occipital regions (Alpha-2 EEG), which we previously reported as an index of the hypersonic effect. Our results showed reciprocal directional changes in Alpha-2 EEGs depending on the frequency of the HFCs presented with audible low-frequency component (LFC). When an HFC above approximately 32 kHz was applied, Alpha-2 EEG increased significantly compared to when only audible sound was applied (positive hypersonic effect), while, when an HFC below approximately 32 kHz was applied, the Alpha-2 EEG decreased (negative hypersonic effect). These findings suggest that the emergence of the hypersonic effect depends on the frequencies of inaudible HFC.

  3. Functional roles of 10 Hz alpha-band power modulating engagement and disengagement of cortical networks in a complex visual motion task.

    PubMed

    Rana, Kunjan D; Vaina, Lucia M

    2014-01-01

    Alpha band power, particularly at the 10 Hz frequency, is significantly involved in sensory inhibition, attention modulation, and working memory. However, the interactions between cortical areas and their relationship to the different functional roles of the alpha band oscillations are still poorly understood. Here we examined alpha band power and the cortico-cortical interregional phase synchrony in a psychophysical task involving the detection of an object moving in depth by an observer in forward self-motion. Wavelet filtering at the 10 Hz frequency revealed differences in the profile of cortical activation in the visual processing regions (occipital and parietal lobes) and in the frontoparietal regions. The alpha rhythm driving the visual processing areas was found to be asynchronous with the frontoparietal regions. These findings suggest a decoupling of the 10 Hz frequency into separate functional roles: sensory inhibition in the visual processing regions and spatial attention in the frontoparietal regions.

  4. A 1.6-kW, 110-kHz dc-dc converter optimized for IGBT's

    NASA Technical Reports Server (NTRS)

    Chen, Keming; Stuart, Thomas A.

    1993-01-01

    A full bridge dc-dc converter using a zero-current and zero-voltage switching technique is described. This circuit utilizes the characteristics of the IGBT to achieve power and frequency combinations that are much higher than previously reported for this device. Experimental results are included for a 1.6-kW, 110-kHz converter with 95 percent efficiency.

  5. Digitally enhanced optical fiber frequency reference.

    PubMed

    McRae, Terry G; Ngo, Silvie; Shaddock, Daniel A; Hsu, Magnus T L; Gray, Malcolm B

    2014-04-01

    We use digitally enhanced heterodyne interferometry to measure the stability of optical fiber laser frequency references. Suppression of laser frequency noise by over four orders of magnitude is achieved using post processing time delay interferometry, allowing us to measure the mechanical stability for frequencies as low as 100 μHz. The performance of the digitally enhanced heterodyne interferometer platform used here is not practically limited by the dynamic range or bandwidth issues that can occur in feedback stabilization systems. This allows longer measurement times, better frequency discrimination, a reduction in spatially uncorrelated noise sources and an increase in interferometer sensitivity. An optical fiber frequency reference with the stability reported here, over a signal band of 20 mHz-1 Hz, has potential for use in demanding environments, such as space-based interferometry missions and optical flywheel applications. PMID:24686596

  6. A simple electrical lumped-element model simulates intra-cochlear sound pressures and cochlear impedance below 2 kHz.

    PubMed

    Marquardt, Torsten; Hensel, Johannes

    2013-11-01

    Low-frequency sounds displace large parts of the basilar membrane (BM) and can have a modulating and possibly disturbing effect on hearing at other frequencies. A better understanding of the transfer of such sounds onto the BM is therefore desirable. Lumped-element models have previously been employed to determine the low-frequency acoustic properties of the cochlea. Although helpful in illustrating schematically the role of the helicotrema, BM compliance, and the round window on low-frequency hearing, these models, when applied quantitatively, have not been able to explain experimental data in detail. Building on these models, an extended electrical analog requires just 13 lumped elements to capture, in surprising detail, the physiologically determined frequency-dependence of intra-cochlear pressure and cochlear impedance between 10 Hz and 2 kHz. The model's verification is based on data from cat, guinea pig, and humans, who differ principally in their low-frequency cochlear acoustics. The modeling data suggest that damping within the helicotrema plays a less prominent role than previously assumed. A resonance feature, which is often observed experimentally near 150 Hz in these animals and near 50 Hz in humans, is presumably a phenomenon local to the apex and not the result of a standing wave between stapes and helicotrema. PMID:24180783

  7. Synthetic aperture acoustic imaging of canonical targets with a 2-15 kHz linear FM chirp

    NASA Astrophysics Data System (ADS)

    Vignola, Joseph F.; Judge, John A.; Good, Chelsea E.; Bishop, Steven S.; Gugino, Peter M.; Soumekh, Mehrdad

    2011-06-01

    Synthetic aperture image reconstruction applied to outdoor acoustic recordings is presented. Acoustic imaging is an alternate method having several military relevant advantages such as being immune to RF jamming, superior spatial resolution, capable of standoff side and forward-looking scanning, and relatively low cost, weight and size when compared to 0.5 - 3 GHz ground penetrating radar technologies. Synthetic aperture acoustic imaging is similar to synthetic aperture radar, but more akin to synthetic aperture sonar technologies owing to the nature of longitudinal or compressive wave propagation in the surrounding acoustic medium. The system's transceiver is a quasi mono-static microphone and audio speaker pair mounted on a rail 5meters in length. Received data sampling rate is 80 kHz with a 2- 15 kHz Linear Frequency Modulated (LFM) chirp, with a pulse repetition frequency (PRF) of 10 Hz and an inter-pulse period (IPP) of 50 milliseconds. Targets are positioned within the acoustic scene at slant range of two to ten meters on grass, dirt or gravel surfaces, and with and without intervening metallic chain link fencing. Acoustic image reconstruction results in means for literal interpretation and quantifiable analyses. A rudimentary technique characterizes acoustic scatter at the ground surfaces. Targets within the acoustic scene are first digitally spotlighted and further processed, providing frequency and aspect angle dependent signature information.

  8. Infrared spectroscopy and Density Functional Theory of crystalline β-2,4,6,8,10,12-hexanitrohexaaziosowurtzitane (β CL-20) in the region of its C-H stretching vibrations

    NASA Astrophysics Data System (ADS)

    Behler, K. D.; Pesce-Rodriguez, R.; Cabalo, J.; Sausa, R.

    2013-10-01

    Molecular vibrational spectroscopy provides a useful tool for material characterization and model verification. We examine the CH stretching fundamental and overtones of energetic material β-2,4,6,8,10,12-hexanitrohexaaziosowurtzitane (β-CL-20) by Raman spectroscopy, Fourier Transform Infrared Spectroscopy, and Laser Photoacoustic Overtone Spectroscopy, and utilize Density Functional Theory to calculate the C-H bond energy of β-CL-20 in a crystal. The spectra reveal four intense and distinct features, whose analysis yields C-H stretching fundamental frequencies and anharmonicity values that range from 3137 to 3170 cm-1 and 53.8 to 58.8 cm-1, respectively. From these data, we estimate an average value of 42,700 cm-1 (5.29 eV) for the C-H bond energy, a value that agrees with our quantum mechanical calculations.

  9. Infrared spectroscopy and Density Functional Theory of crystalline β-2,4,6,8,10,12-hexanitrohexaaziosowurtzitane (β CL-20) in the region of its C-H stretching vibrations.

    PubMed

    Behler, K D; Pesce-Rodriguez, R; Cabalo, J; Sausa, R

    2013-10-01

    Molecular vibrational spectroscopy provides a useful tool for material characterization and model verification. We examine the CH stretching fundamental and overtones of energetic material β-2,4,6,8,10,12-hexanitrohexaaziosowurtzitane (β-CL-20) by Raman spectroscopy, Fourier Transform Infrared Spectroscopy, and Laser Photoacoustic Overtone Spectroscopy, and utilize Density Functional Theory to calculate the C-H bond energy of β-CL-20 in a crystal. The spectra reveal four intense and distinct features, whose analysis yields C-H stretching fundamental frequencies and anharmonicity values that range from 3137 to 3170 cm(-1) and 53.8 to 58.8 cm(-1), respectively. From these data, we estimate an average value of 42,700 cm(-1) (5.29 eV) for the C-H bond energy, a value that agrees with our quantum mechanical calculations. PMID:23832164

  10. Suggestions for Curriculum Development [And] Handbook High School Grades, Part D, 10-12. Environmental Education Interdependence: A Concept Approach. Revised.

    ERIC Educational Resources Information Center

    King, David C.; Wood, Jayne Millar

    Two booklets comprise the grades 10-12 component of a series of guides for incorporating environmental education into the existing curriculum. The guide and handbook emphasize a multidisciplinary approach, use the concept of interdependence as an organizing theme, and offer suggestions for using the local community as a resource. The guide…

  11. 40 Hz Auditory Steady-State Response Is a Pharmacodynamic Biomarker for Cortical NMDA Receptors.

    PubMed

    Sivarao, Digavalli V; Chen, Ping; Senapati, Arun; Yang, Yili; Fernandes, Alda; Benitex, Yulia; Whiterock, Valerie; Li, Yu-Wen; Ahlijanian, Michael K

    2016-08-01

    Schizophrenia patients exhibit dysfunctional gamma oscillations in response to simple auditory stimuli or more complex cognitive tasks, a phenomenon explained by reduced NMDA transmission within inhibitory/excitatory cortical networks. Indeed, a simple steady-state auditory click stimulation paradigm at gamma frequency (~40 Hz) has been reproducibly shown to reduce entrainment as measured by electroencephalography (EEG) in patients. However, some investigators have reported increased phase locking factor (PLF) and power in response to 40 Hz auditory stimulus in patients. Interestingly, preclinical literature also reflects this contradiction. We investigated whether a graded deficiency in NMDA transmission can account for such disparate findings by administering subanesthetic ketamine (1-30 mg/kg, i.v.) or vehicle to conscious rats (n=12) and testing their EEG entrainment to 40 Hz click stimuli at various time points (~7-62 min after treatment). In separate cohorts, we examined in vivo NMDA channel occupancy and tissue exposure to contextualize ketamine effects. We report a robust inverse relationship between PLF and NMDA occupancy 7 min after dosing. Moreover, ketamine could produce inhibition or disinhibition of the 40 Hz response in a temporally dynamic manner. These results provide for the first time empirical data to understand how cortical NMDA transmission deficit may lead to opposite modulation of the auditory steady-state response (ASSR). Importantly, our findings posit that 40 Hz ASSR is a pharmacodynamic biomarker for cortical NMDA function that is also robustly translatable. Besides schizophrenia, such a functional biomarker may be of value to neuropsychiatric disorders like bipolar and autism spectrum where 40 Hz ASSR deficits have been documented. PMID:26837462

  12. Design and performance of a 250 Hz alexandrite laser

    SciTech Connect

    Sam, R.C.; Yeh, J.J.; Leslie, K.R.; Rapoport, W.R.

    1988-06-01

    The design, analysis, and performance of a 250 Hz alexandrite laser are described. Built as the wavelength selective laser for a molecular laser isotope separation program, the laser has to satisfy specifications on its tuning band, linewidth, output energy, temporal behavior, and repetition rate required by the process. The key design feature is the use of a tandem rod oscillator with concave curvature on rod ends for thermal lensing compensation. A model was developed to project the stability range and beam quality relative to repetition rate. The performance results of a delivered system are presented and future developments are discussed.

  13. 1-kHz-repetition-rate femtosecond Raman laser

    NASA Astrophysics Data System (ADS)

    Didenko, N. V.; Konyashchenko, A. V.; Kostryukov, P. V.; Losev, L. L.; Pazyuk, V. S.; Tenyakov, S. Yu

    2016-07-01

    A femtosecond Raman laser utilising compressed hydrogen is experimentally investigated under pumping by radiation from a 1-kHz-repetition-rate Ti : sapphire laser. In the regime of double-pulse pumping, the conditions are determined, which correspond to the minimal energy dispersion of Stokes pulses. The optical scheme is realised, which is capable of ensuring the long-term stability of the average power of the first Stokes component with a variation of less than 2%. The Stokes pulses are produced with a pulse duration of 60 fs and energy of 0.26 mJ at a conversion efficiency of 14%.

  14. FPGA implementation of high-frequency multiple PWM for variable voltage variable frequency controller

    NASA Astrophysics Data System (ADS)

    Boumaaraf, Abdelâali; Mohamadi, Tayeb; Gourmat, Laïd

    2016-07-01

    In this paper, we present the FPGA implementation of the multiple pulse width modulation (MPWM) signal generation with repetition of data segments, applied to the variable frequency variable voltage systems and specially at to the photovoltaic water pumping system, in order to generate a signal command very easily between 10hz to 60 hz with a small frequency and reduce the cost of the control system.

  15. Rhythmic 3–4 Hz discharge is insufficient to produce cortical BOLD fMRI decreases in generalized seizures

    PubMed Central

    Youngblood, Mark W.; Chen, William C.; Mishra, Asht M.; Enamandram, Sheila; Sanganahalli, Basavaraju G.; Motelow, Joshua E.; Bai, Harrison X.; Frohlich, Flavio; Gribizis, Alexandra; Lighten, Alexis; Hyder, Fahmeed; Blumenfeld, Hal

    2015-01-01

    Absence seizures are transient episodes of impaired consciousness accompanied by 3–4 Hz spike-wave discharge on electroencephalography (EEG). Human functional magnetic resonance imaging (fMRI) studies have demonstrated widespread cortical decreases in the blood oxygen-level dependent (BOLD) signal that may play an important role in the pathophysiology of these seizures. Animal models could provide an opportunity to investigate the fundamental mechanisms of these changes, however they have so far failed to consistently replicate the cortical fMRI decreases observed in human patients. This may be due to important differences between human seizures and animal models, including a lack of cortical development in rodents or differences in the frequency of rodent (7–8 Hz) and human (3–4 Hz) spike-wave discharge. To examine the possible contributions of these differences, we developed a ferret model that exhibits 3–4 Hz spike-wave seizures in the presence of a sulcated cortex. Measurements of BOLD fMRI and simultaneous EEG demonstrated cortical fMRI increases during and following spike-wave seizures in ferrets. However unlike human patients, significant fMRI decreases were not observed. The lack of fMRI decreases was consistent across seizures of different durations, discharge frequencies, and anesthetic regimes, and using fMRI analysis models similar to human patients. In contrast, generalized tonic-clonic seizures under the same conditions elicited sustained postictal fMRI decreases, verifying that the lack of fMRI decreases with spike-wave was not due to technical factors. These findings demonstrate that 3–4 Hz spike-wave discharge in a sulcated animal model does not necessarily produce fMRI decreases, leaving the mechanism for this phenomenon open for further investigation. PMID:25562830

  16. Near shot-noise-level relative frequency stabilization of a laser-diode-pumped Nd:YVO{sub 4} microchip laser

    SciTech Connect

    Hyodo, M.; Carty, T.; Sakai, K.

    1996-08-01

    A laser-diode-pumped Nd:YVO{sub 4} microchip laser was built and actively frequency stabilized relative to a Fabry{endash}Perot cavity with the frequency-modulated sideband technique. The error signal reaches the shot-noise level of 7.4 mHz/Hz around 1 kHz. Excess intensity noise sets a lower limit of 16.5 mHz/Hz for the relative frequency noise, corresponding to a spectral linewidth of 860 {mu}Hz. We discuss the method for reconstructing the actual frequency deviation from the observed error signal. {copyright} {ital 1996 Optical Society of America.}

  17. Resonant frequency does not predict high-frequency chest compression settings that maximize airflow or volume.

    PubMed

    Luthy, Sarah K; Marinkovic, Aleksandar; Weiner, Daniel J

    2011-06-01

    High-frequency chest compression (HFCC) is a therapy for cystic fibrosis (CF). We hypothesized that the resonant frequency (f(res)), as measured by impulse oscillometry, could be used to determine what HFCC vest settings produce maximal airflow or volume in pediatric CF patients. In 45 subjects, we studied: f(res), HFCC vest frequencies that subjects used (f(used)), and the HFCC vest frequencies that generated the greatest volume (f(vol)) and airflow (f(flow)) changes as measured by pneumotachometer. Median f(used) for 32 subjects was 14 Hz (range, 6-30). The rank order of the three most common f(used) was 15 Hz (28%) and 12 Hz (21%); three frequencies tied for third: 10, 11, and 14 Hz (5% each). Median f(res) for 43 subjects was 20.30 Hz (range, 7.85-33.65). Nineteen subjects underwent vest-tuning to determine f(vol) and f(flow). Median f(vol) was 8 Hz (range, 6-30). The rank order of the three most common f(vol) was: 8 Hz (42%), 6 Hz (32%), and 10 Hz (21%). Median f(flow) was 26 Hz (range, 8-30). The rank order of the three most common f(flow) was: 30 Hz (26%) and 28 Hz (21%); three frequencies tied for third: 8, 14, and 18 Hz (11% each). There was no correlation between f(used) and f(flow) (r(2)  = -0.12) or f(vol) (r(2) = 0.031). There was no correlation between f(res) and f(flow) (r(2)  = 0.19) or f(vol) (r(2) = 0.023). Multivariable analysis showed no independent variables were predictive of f(flow) or f(vol). Vest-tuning may be required to optimize clinical utility of HFCC. Multiple HFCC frequencies may need to be used to incorporate f(flow) and f(vol).

  18. 40-Hz oscillations underlying perceptual binding in young and older adults.

    PubMed

    Ross, Bernhard; Fujioka, Takako

    2016-07-01

    Auditory object perception requires binding of elementary features of complex stimuli. Synchronization of high-frequency oscillation in neural networks has been proposed as an effective alternative to binding via hard-wired connections because binding in an oscillatory network can be dynamically adjusted to the ever-changing sensory environment. Previously, we demonstrated in young adults that gamma oscillations are critical for sensory integration and found that they were affected by concurrent noise. Here, we aimed to support the hypothesis that stimulus evoked auditory 40-Hz responses are a component of thalamocortical gamma oscillations and examined whether this oscillatory system may become less effective in aging. In young and older adults, we recorded neuromagnetic 40-Hz oscillations, elicited by monaural amplitude-modulated sound. Comparing responses in quiet and under contralateral masking with multitalker babble noise revealed two functionally distinct components of auditory 40-Hz responses. The first component followed changes in the auditory input with high fidelity and was of similar amplitude in young and older adults. The second, significantly smaller in older adults, showed a 200-ms interval of amplitude and phase rebound and was strongly attenuated by contralateral noise. The amplitude of the second component was correlated with behavioral speech-in-noise performance. Concurrent noise also reduced the P2 wave of auditory evoked responses at 200-ms latency, but not the earlier N1 wave. P2 modulation was reduced in older adults. The results support the model of sensory binding through thalamocortical gamma oscillations. Limitation of neural resources for this process in older adults may contribute to their speech-in-noise understanding deficits. PMID:27080577

  19. On the Solar Origin of the 220.7 μHz Signal

    NASA Astrophysics Data System (ADS)

    Jiménez, A.; García, R. A.

    2009-12-01

    Gravity modes in the Sun have been long searched for during the past decades. Using their asymptotic properties García et al. (2007) found the signature of the dipole g modes analyzing an spectral window between 25 and 140 μHz of velocity power spectrum obtained from the Global Oscillations at Low Frequencies (GOLF)/SoHO instrument. Using this result it has been possible to check some properties of the structure of the solar interior (García, Mathur & Ballot 2008) as well as some indications of the dynamics of the core. However, the individual detection of such modes remains evasive and they are needed to really improve our knowledge of the deepest layers in the Sun (Mathur et al. 2008). In this work we study the signal at 220.7 μHz which is present in most of the helioseismic instruments during the last 10 years. This signal has been previously identified as part of a g-mode candidate in the GOLF data (Turck-Chièze et al. 2004; Mathur et al. 2007) and in SPM/Variability of solar IRradiance and Gravity Oscillations (VIRGO) (García et al. 2008) with more than 90% confidence level. It could be labeled as the l=2 n=-3 g mode as it is in the region were this mode is expected. We have checked the possibility that the 220.7 μHz signal could have an instrumental origin without success by analyzing all available housekeeping data as well as information on the roll, pitch and yaw of the SoHO spacecraft. In consequence, we are confident that this signal has a solar origin.

  20. A center frequency adjustable narrow band filter for the detection of weak single frequency signal.

    PubMed

    Xin, Yunhong; Xiang, ZhenMing; Dong, LeMing; Zhu, Bing; Cao, Hui; Fang, Yu

    2014-04-01

    We describe and implement a center frequency adjustable narrow band filter based on the crystal filter for the detection of weak single frequency signal. It is formed by a multiplier, a direct digital frequency synthesizer, a multi-stage crystal bandpass filter, and a micro control unit which is used to set the center frequency of the filter. A theoretical study is proposed and experimentally validated. The test results show that the 3 db and 20 db bandwidths are 0.84 Hz and 2.73 Hz, respectively, and the filter system can effectively detect the signal with amplitude below 1 μV and a frequency which ranges from 10 Hz to the frequency that is mainly limited by the components applied.

  1. Psychophysical tuning curves at very high frequencies

    NASA Astrophysics Data System (ADS)

    Yasin, Ifat; Plack, Christopher J.

    2005-10-01

    For most normal-hearing listeners, absolute thresholds increase rapidly above about 16 kHz. One hypothesis is that the high-frequency limit of the hearing-threshold curve is imposed by the transmission characteristics of the middle ear, which attenuates the sound input [Masterton et al., J. Acoust. Soc. Am. 45, 966-985 (1969)]. An alternative hypothesis is that the high-frequency limit of hearing is imposed by the tonotopicity of the cochlea [Ruggero and Temchin, Proc. Nat. Acad. Sci. U.S.A. 99, 13206-13210 (2002)]. The aim of this study was to test these hypotheses. Forward-masked psychophysical tuning curves (PTCs) were derived for signal frequencies of 12-17.5 kHz. For the highest signal frequencies, the high-frequency slopes of some PTCs were steeper than the slope of the hearing-threshold curve. The results also show that the human auditory system displays frequency selectivity for characteristic frequencies (CFs) as high as 17 kHz, above the frequency at which absolute thresholds begin to increase rapidly. The findings suggest that, for CFs up to 17 kHz, the high-frequency limitation in humans is imposed in part by the middle-ear attenuation, and not by the tonotopicity of the cochlea.

  2. Cortico-muscular coupling and motor performance are modulated by 20 Hz transcranial alternating current stimulation (tACS) in Parkinson’s disease

    PubMed Central

    Krause, Vanessa; Wach, Claudia; Südmeyer, Martin; Ferrea, Stefano; Schnitzler, Alfons; Pollok, Bettina

    2014-01-01

    Parkinson’s disease (PD) is associated with pathologically altered oscillatory activity. While synchronized oscillations between 13 and 30 Hz are increased within a cortico-subcortical network, cortico-muscular coupling (CMC) is decreased. The present study aims at investigating the effect of non-invasive transcranial alternating current stimulation (tACS) of the primary motor cortex (M1) on motor symptoms and motor-cortical oscillations in PD. In 10 PD patients and 10 healthy control subjects, static isometric contraction, dynamic fast finger tapping, and diadochokinesia of the more severely affected hand were investigated prior to and shortly after tACS of the contralateral M1 at 10 Hz vs. 20 Hz vs. sham. During isometric contraction, neuromagnetic activity was recorded using magnetoencephalography. 20 Hz tACS attenuated beta band CMC during isometric contraction and amplitude variability during finger tapping in PD patients but not in healthy control subjects. 10 Hz tACS yielded no significant after-effects. The present data suggest that PD is associated with pathophysiological alterations which abet a higher responsiveness toward frequency-specific tACS – possibly due to pathologically altered motor-cortical oscillatory synchronization at frequencies between 13 and 30 Hz. PMID:24474912

  3. Slip-stacking Dynamics and the 20 Hz Booster

    SciTech Connect

    Eldred, Jeffery; Zwaska, Robert

    2015-03-01

    Slip-stacking is an accumulation technique used at Fermilab since 2004 which nearly doubles the proton intensity. The Proton Improvement Plan II intensity upgrades require a reduction in slip-stacking losses by approximately a factor of 2. We study the single-particle dynamics that determine the stability of slip-stacking particles. We introduce universal area factors to calculate the available phase space area for any set of beam parameters without individual simulation. We show the particle loss as a function of time. We calculate the injection efficiency as a function of longitudinal emittance and aspect-ratio. We demonstrate that the losses from RF single particle dynamics can be reduced by a factor of 4-10 (depending on beam parameters) by upgrading the Fermilab Booster from a 15-Hz cycle-rate to a 20-Hz cycle-rate. We recommend a change in injection scheme to eliminate the need for a greater momentum aperture in the Fermilab Recycler.

  4. Endocrinological effects of strong 60-Hz electric fields on rats

    SciTech Connect

    Free, M.J.; Kaune, W.T.; Phillips, R.D.; Cheng, H.C.

    1981-01-01

    Adult male rats were exposed or sham-exposed to 60-Hz electric fields without spark discharges, ozone, or significant levels or other secondary variables. No effects were discharges, ozone, or significant levels of other secondary variables. No effects were observed on body weights or plasma hormone levels after 30 days of exposure at an effective field strength of 68 kV/m. After 120 days of exposure (effective field strength = 64 kV/m), effects were inconsistent, with signficant reductions in body weight and plasma levels of follicle-stimulating hormone and corticosterone occurring in one replicate experiment but not in the other. Plasma testosterone levels were significantly reduced after 120 days of exposure in one experiment, with a similar but not statistically significant reduction in a replicate experiment. Weanling rats, exposed or sham-exposed in electric fields with an effective field strength of 80 kV/m from 20 to 56 days of age, exhibited identical or closely similar growth trends in body and organ weights. Hormone levels in exposed and sham-exposed groups were also similar. However, there was an apparent phase shift between the two groups in the cyclic variations of concentrations of hormones at different stages of development, particularly with respect to follicle-stimulating hormone and corticosterone. We concluded that 60-Hz electric fields may bring about subtle changes in the endocrine system of rats, and that these changes may be related to alterations in episodic rhythms.

  5. Frequency-dependent ultrasound-induced transformation in E. coli.

    PubMed

    Deeks, Jeremy; Windmill, James; Agbeze-Onuma, Maduka; Kalin, Robert M; Argondizza, Peter; Knapp, Charles W

    2014-12-01

    Ultrasound-enhanced gene transfer (UEGT) is continuing to gain interest across many disciplines; however, very few studies investigate UEGT efficiency across a range of frequencies. Using a variable frequency generator, UEGT was tested in E. coli at six ultrasonic frequencies. Results indicate frequency can significantly influence UEGT efficiency positively and negatively. A frequency of 61 kHz improved UEGT efficiency by ~70 % higher, but 99 kHz impeded UEGT to an extent worse than no ultrasound exposure. The other four frequencies (26, 133, 174, and 190 kHz) enhanced transformation compared to no ultrasound, but efficiencies did not vary. The influence of frequency on UEGT efficiency was observed across a range of operating frequencies. It is plausible that frequency-dependent dynamics of mechanical and chemical energies released during cavitational-bubble collapse (CBC) are responsible for observed UEGT efficiencies.

  6. Effect of power frequency harmonics on magnetic field measurements.

    PubMed

    Isokorpi, J; Rautee, J; Keikko, T; Korpinen, L

    2000-03-01

    This paper presents a study of the effect of harmonic frequencies on magnetic field measurements. We introduced magnetic field meters in a known magnetic field of different frequencies: power frequency (50 Hz) as well as 3rd (150 Hz) and 5th (250 Hz) harmonic frequencies. Two magnetic field levels (0.25 A and 2.5 A) were used. A Helmholtz coil was applied to generate an exact magnetic field. The difference between the measurement results at harmonic frequencies and at power frequency was analyzed using the t-test for matched pairs. The test results show significant differences (P< or =0.01) for 13 out of 28 tests carried out, which is probably due to a curved frequency response near the power frequency. It is, therefore, essential to consider harmonic frequencies in magnetic field measurements in practice.

  7. Design and testing of 45 kV, 50 kHz pulse power supply for dielectric barrier discharges

    NASA Astrophysics Data System (ADS)

    Sharma, Surender Kumar; Shyam, Anurag

    2016-10-01

    The design, construction, and testing of high frequency, high voltage pulse power supply are reported. The purpose of the power supply is to generate dielectric barrier discharges for industrial applications. The power supply is compact and has the advantage of low cost, over current protection, and convenient control for voltage and frequency selection. The power supply can generate high voltage pulses of up to 45 kV at the repetitive frequency range of 1 kHz-50 kHz with 1.2 kW input power. The output current of the power supply is limited to 500 mA. The pulse rise time and fall time are less than 2 μs and the pulse width is 2 μs. The power supply is short circuit proof and can withstand variable plasma load conditions. The power supply mainly consists of a half bridge series resonant converter to charge an intermediate capacitor, which discharges through a step-up transformer at high frequency to generate high voltage pulses. Semiconductor switches and amorphous cores are used for power modulation at higher frequencies. The power supply is tested with quartz tube dielectric barrier discharge load and worked stably. The design details and the performance of the power supply on no load and dielectric barrier discharge load are presented.

  8. Optimization of EEG frequency bands for improved diagnosis of Alzheimer disease.

    PubMed

    Elgendi, Mohamed; Vialatte, Francois; Cichocki, Andrzej; Latchoumane, Charles; Jeong, Jaesung; Dauwels, Justin

    2011-01-01

    Many clinical studies have shown that electroencephalograms (EEG) of Alzheimer patients (AD) often have an abnormal power spectrum. In this paper a frequency band analysis of AD EEG signals is presented, with the aim of improving the diagnosis of AD from EEG signals. Relative power in different EEG frequency bands is used as features to distinguish between AD patients and healthy control subjects. Many different frequency bands between 4 and 30 Hz are systematically tested, besides the traditional frequency bands, e.g., theta band (4-8 Hz). The discriminative power of the resulting spectral features is assessed through statistical tests (Mann-Whitney U test). Moreover, linear discriminant analysis is conducted with those spectral features. The optimized frequency ranges (4-7 Hz, 8-15 Hz, 19-24 Hz) yield substantially better classification performance than the traditional frequency bands (4-8 Hz, 8-12 Hz, 12-30 Hz); the frequency band 4-7 Hz is the optimal frequency range for detecting AD, which is similar to the classical theta band. The frequency bands were also optimized as features through leave-one-out crossvalidation, resulting in error-free classification. The optimized frequency bands may improve existing EEG based diagnostic tools for AD. Additional testing on larger AD datasets is required to verify the effectiveness of the proposed approach.

  9. Investigation of geomagnetic disturbances (F=1-5 Hz) before strong EQs in Kamchatka region

    NASA Astrophysics Data System (ADS)

    Kopytenko, Y.; Ismaguilov, V.; Schekotov, A.; Molchanov, O.; Hayakawa, M.

    2007-05-01

    Regular observations of ULF electromagnetic disturbances at st. Karymshino in seismic active zone of Kamchatka peninsula were carried out by induction three-component high-sensitive magnetometer during 2001- 2003 years. Five seismic active periods with strong earthquakes (M>5) were displayed during this period. These EQs occurred at the Pacific at 20-60 km depth at 100-140 km distances to the East from the st. Karymshino. Analysis of normalized dynamic power spectra of data of high-sensitive (0.2 pT/sqrt(Hz)) three- component induction magnetometer achieved a significant disorder of daily variation and increasing of the magnetic disturbance intensities (from 0.2 to ~ 1 pT) in the whole investigated frequency range (1 - 5 Hz). The anomaly intensity increasing was observed during the 12-18 hours before main seismic shocks. Maximum of the increasing occurred during 4-6 hours before the EQs. A sharp decreasing of the magnetic disturbance intensities was observed 2-4 hours before the EQs. We suppose that physical processes in a hearth of forthcoming EQ lead to an irreversible avalanche-like formation of cracks and stimulation of the ULF electromagnetic disturbances.

  10. Are the kHz QPO Lags in Neutron Star 4U 1608–52 due to Reverberation?

    NASA Astrophysics Data System (ADS)

    Cackett, Edward M.

    2016-08-01

    X-ray reverberation lags have recently been discovered in both active galactic nuclei (AGNs) and black hole X-ray binaries. A recent study of the neutron star low-mass X-ray binary (LMXB) 4U 1608‑52 has also shown significant lags, whose properties hint at a reverberation origin. Here, we adapt general relativistic ray tracing impulse response functions used to model X-ray reverberation in AGNs for neutron star LMXBs. Assuming that relativistic reflection forms the broad iron line and associated reflection continuum, we use reflection fits to the energy spectrum along with the impulse response functions to calculate the expected lags as a function of energy over the range of observed kHz quasi-periodic oscillation (QPO) frequencies in 4U 1608‑52. We find that the lag energy spectrum is expected to increase with increasing energy above 8 keV, while the observed lags in 4U 1608‑52 show the opposite behavior. This demonstrates that the lags in the lower kHz QPO of 4U 1608‑52 are not solely due to reverberation. We do note, however, that the models appear to be more consistent with the much flatter lag energy spectrum observed in the upper kHz QPO of several neutron star LMXBs, suggesting that lower and upper kHz QPOs may have different origins.

  11. DISCOVERY OF A 7 mHz X-RAY QUASI-PERIODIC OSCILLATION FROM THE MOST MASSIVE STELLAR-MASS BLACK HOLE IC 10 X-1

    SciTech Connect

    Pasham, Dheeraj R.; Mushotzky, Richard F.; Strohmayer, Tod E. E-mail: richard@astro.umd.edu

    2013-07-10

    We report the discovery with XMM-Newton of an Almost-Equal-To 7 mHz X-ray (0.3-10.0 keV) quasi-periodic oscillation (QPO) from the eclipsing, high-inclination black hole binary IC 10 X-1. The QPO is significant at >4.33{sigma} confidence level and has a fractional amplitude (% rms) and a quality factor, Q {identical_to} {nu}/{Delta}{nu}, of Almost-Equal-To 11 and 4, respectively. The overall X-ray (0.3-10.0 keV) power spectrum in the frequency range 0.0001-0.1 Hz can be described by a power-law with an index of Almost-Equal-To - 2, and a QPO at 7 mHz. At frequencies {approx}>0.02 Hz there is no evidence for significant variability. The fractional amplitude (rms) of the QPO is roughly energy-independent in the energy range of 0.3-1.5 keV. Above 1.5 keV the low signal-to-noise ratio of the data does not allow us to detect the QPO. By directly comparing these properties with the wide range of QPOs currently known from accreting black hole and neutron stars, we suggest that the 7 mHz QPO of IC 10 X-1 may be linked to one of the following three categories of QPOs: (1) the 'heartbeat' mHz QPOs of the black hole sources GRS 1915+105 and IGR J17091-3624, or (2) the 0.6-2.4 Hz 'dipper QPOs' of high-inclination neutron star systems, or (3) the mHz QPOs of Cygnus X-3.

  12. Effects of a 60 Hz Magnetic Field Exposure Up to 3000 μT on Human Brain Activation as Measured by Functional Magnetic Resonance Imaging

    PubMed Central

    Legros, Alexandre; Modolo, Julien; Brown, Samantha; Roberston, John; Thomas, Alex W.

    2015-01-01

    Several aspects of the human nervous system and associated motor and cognitive processes have been reported to be modulated by extremely low-frequency (ELF, < 300 Hz) time-varying Magnetic Fields (MF). Due do their worldwide prevalence; power-line frequencies (60 Hz in North America) are of particular interest. Despite intense research efforts over the last few decades, the potential effects of 60 Hz MF still need to be elucidated, and the underlying mechanisms to be understood. In this study, we have used functional Magnetic Resonance Imaging (fMRI) to characterize potential changes in functional brain activation following human exposure to a 60 Hz MF through motor and cognitive tasks. First, pilot results acquired in a first set of subjects (N=9) were used to demonstrate the technical feasibility of using fMRI to detect subtle changes in functional brain activation with 60 Hz MF exposure at 1800 μT. Second, a full study involving a larger cohort of subjects tested brain activation during 1) a finger tapping task (N=20), and 2) a mental rotation task (N=21); before and after a one-hour, 60 Hz, 3000 μT MF exposure. The results indicate significant changes in task-induced functional brain activation as a consequence of MF exposure. However, no impact on task performance was found. These results illustrate the potential of using fMRI to identify MF-induced changes in functional brain activation, suggesting that a one-hour 60 Hz, 3000 μT MF exposure can modulate activity in specific brain regions after the end of the exposure period (i.e., residual effects). We discuss the possibility that MF exposure at 60 Hz, 3000 μT may be capable of modulating cortical excitability via a modulation of synaptic plasticity processes. PMID:26214312

  13. Discovery of a 7 mHz X-Ray Quasi-Periodic Oscillation from the Most Massive Stellar-Mass Black Hole IC 10 X-1

    NASA Technical Reports Server (NTRS)

    Pasham, Dheeraj R.; Strohmayer, Tod E.; Mushotzky, Richard F.

    2013-01-01

    We report the discovery with XMM-Newton of an approx.. = 7 mHz X-ray (0.3-10.0 keV) quasi-periodic oscillation (QPO) from the eclipsing, high-inclination black hole binary IC 10 X-1. The QPO is significant at >4.33 sigma confidence level and has a fractional amplitude (% rms) and a quality factor, Q is identical with nu/delta nu, of approx. = 11 and 4, respectively. The overall X-ray (0.3-10.0 keV) power spectrum in the frequency range 0.0001-0.1 Hz can be described by a power-law with an index of approx. = -2, and a QPO at 7 mHz. At frequencies approx. > 0.02 Hz there is no evidence for significant variability. The fractional amplitude (rms) of the QPO is roughly energy-independent in the energy range of 0.3-1.5 keV. Above 1.5 keV the low signal-to-noise ratio of the data does not allow us to detect the QPO. By directly comparing these properties with the wide range of QPOs currently known from accreting black hole and neutron stars, we suggest that the 7 mHz QPO of IC 10 X-1 may be linked to one of the following three categories of QPOs: (1) the "heartbeat" mHz QPOs of the black hole sources GRS 1915+105 and IGR J17091-3624, or (2) the 0.6-2.4 Hz "dipper QPOs" of high-inclination neutron star systems, or (3) the mHz QPOs of Cygnus X-3.

  14. Corticomuscular coherence is tuned to the spontaneous rhythmicity of speech at 2-3 Hz.

    PubMed

    Ruspantini, Irene; Saarinen, Timo; Belardinelli, Paolo; Jalava, Antti; Parviainen, Tiina; Kujala, Jan; Salmelin, Riitta

    2012-03-14

    Human speech features rhythmicity that frames distinctive, fine-grained speech patterns. Speech can thus be counted among rhythmic motor behaviors that generally manifest characteristic spontaneous rates. However, the critical neural evidence for tuning of articulatory control to a spontaneous rate of speech has not been uncovered. The present study examined the spontaneous rhythmicity in speech production and its relationship to cortex-muscle neurocommunication, which is essential for speech control. Our MEG results show that, during articulation, coherent oscillatory coupling between the mouth sensorimotor cortex and the mouth muscles is strongest at the frequency of spontaneous rhythmicity of speech at 2-3 Hz, which is also the typical rate of word production. Corticomuscular coherence, a measure of efficient cortex-muscle neurocommunication, thus reveals behaviorally relevant oscillatory tuning for spoken language.

  15. Final Report. Supplementary comparison of 50/60 Hz energy SIM.EM-S7

    NASA Astrophysics Data System (ADS)

    Carranza, R.; Campos, S.; Castruita, A.; Nelson, T.; Ribeiro, A. M.; So, E.; Spaggiari, A.; Slomovitz, D.; Izquierdo, D.; Postigo, H.; Díaz, H.; Sanchez, H.; Gonzalez, J.; Ramos, R.; Zipaquira, A.

    2016-01-01

    From 2010 to 2012, a key comparison of energy standards at 50/60 Hz was conducted in the SIM region. The comparison included measurements of active and reactive energy at three frequencies, aiming at providing support to high accuracy measurement needs of reactive energy. This work presents the results of the SIM.EM-S7 supplementary comparison. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  16. Mechanism for generation of 2-3 kHz radiation in the outer heliosphere

    NASA Technical Reports Server (NTRS)

    Macek, W. M.

    1995-01-01

    The question of how low-frequency non-thermal radio emissions at the boundary of the heliosphere might be generated is considered. The mechanism consists of two steps. First, the beam of energetic electrons generates a high level of electrostatic Langmuir plasma waves. Second, electromagnetic radiation results from the non-linear interaction between Langmuir waves. Intensity of radio emissions at 2 to 3 kHz detected by the Voyager plasma wave instrument in the outer heliosphere can be explained provided that the electron beams generating Langmuir waves exist also in the postshock plasma due to secondary shocks in the compressed solar wind beyond the termination shock. Modification of the heliospheric shocks by the cosmic ray pressure is also taken into account. The field strengths of Langmuir waves required to generate the second harmonic emissions are of 50 to 100 microvolts per meter. These waves may be observed in situ by Voyager 1 and 2 in the near future.

  17. Precision frequency measurements with interferometric weak values

    NASA Astrophysics Data System (ADS)

    Starling, David J.; Dixon, P. Ben; Jordan, Andrew N.; Howell, John C.

    2010-12-01

    We demonstrate an experiment which utilizes a Sagnac interferometer to measure a change in optical frequency of 129 ± 7 kHz/Hz with only 2 mW of continuous-wave, single-mode input power. We describe the measurement of a weak value and show how even higher-frequency sensitivities may be obtained over a bandwidth of several nanometers. This technique has many possible applications, such as precision relative frequency measurements and laser locking without the use of atomic lines.

  18. 100 kHz Mueller polarimeter in reflection configuration.

    PubMed

    Le Gratiet, Aymeric; Rivet, Sylvain; Dubreuil, Matthieu; Le Grand, Yann

    2015-02-15

    A new setup is proposed to perform high-speed Mueller polarimetry by spectral coding of polarization in a reflection configuration. The system uses a swept laser source and a photodiode, which results in a simple optical setup that allows measurement of Mueller matrices at 100 kHz repetition rate. A special focus is made on the influence of the cube beam splitter polarimetric response, which is essential to measurements in a reflection configuration. The instrument is first validated on reference samples for single-point measurements, and the effect of a proper system calibration is also demonstrated on polarimetric images. The device is intended to be implemented within a laser scanning microscope to perform multimodal imaging (confocal/multiphoton and Mueller polarimetry). PMID:25680171

  19. PET imaging of the 40 Hz auditory steady state response.

    PubMed

    Reyes, Samuel A; Salvi, Richard J; Burkard, Robert F; Coad, Mary Lou; Wack, David S; Galantowicz, Paul J; Lockwood, Alan H

    2004-08-01

    The auditory steady state response (aSSR) is an oscillatory electrical potential recorded from the scalp induced by amplitude-modulated (AM) or click/tone burst stimuli. Its clinical utility has been limited by uncertainty regarding the specific areas of the brain involved in its generation. To identify the generators of the aSSR, 15O-water PET imaging was used to locate the regions of the brain activated by a steady 1 kHz pure tone, the same tone amplitude modulated (AM) at 40 Hz and the specific regions of the brain responsive to the AM component of the stimulus relative to the continuous tone. The continuous tone produced four clusters of activation. The boundaries of these activated clusters extended to include regions in left primary auditory cortex, right non-primary auditory cortex, left thalamus, and left cingulate. The AM tone produced three clusters of activation. The boundaries of these activated clusters extended to include primary auditory cortex bilaterally, left medial geniculate and right middle frontal gyrus. Two regions were specifically responsive to the AM component of the stimulus. These activated clusters extended to include the right anterior cingulate near frontal cortex and right auditory cortex. We conclude that cortical sites, including areas outside primary auditory cortex, are involved in generating the aSSR. There was an unexpected difference between morning and afternoon session scans that may reflect a pre- versus post-prandial state. These results support the hypothesis that a distributed resonating circuit mediates the generation of the aSSR.

  20. Interpretations of Frequency Domain Analyses of Neural Entrainment: Periodicity, Fundamental Frequency, and Harmonics

    PubMed Central

    Zhou, Hong; Melloni, Lucia; Poeppel, David; Ding, Nai

    2016-01-01

    Brain activity can follow the rhythms of dynamic sensory stimuli, such as speech and music, a phenomenon called neural entrainment. It has been hypothesized that low-frequency neural entrainment in the neural delta and theta bands provides a potential mechanism to represent and integrate temporal information. Low-frequency neural entrainment is often studied using periodically changing stimuli and is analyzed in the frequency domain using the Fourier analysis. The Fourier analysis decomposes a periodic signal into harmonically related sinusoids. However, it is not intuitive how these harmonically related components are related to the response waveform. Here, we explain the interpretation of response harmonics, with a special focus on very low-frequency neural entrainment near 1 Hz. It is illustrated why neural responses repeating at f Hz do not necessarily generate any neural response at f Hz in the Fourier spectrum. A strong neural response at f Hz indicates that the time scales of the neural response waveform within each cycle match the time scales of the stimulus rhythm. Therefore, neural entrainment at very low frequency implies not only that the neural response repeats at f Hz but also that each period of the neural response is a slow wave matching the time scale of a f Hz sinusoid. PMID:27375465

  1. Interpretations of Frequency Domain Analyses of Neural Entrainment: Periodicity, Fundamental Frequency, and Harmonics.

    PubMed

    Zhou, Hong; Melloni, Lucia; Poeppel, David; Ding, Nai

    2016-01-01

    Brain activity can follow the rhythms of dynamic sensory stimuli, such as speech and music, a phenomenon called neural entrainment. It has been hypothesized that low-frequency neural entrainment in the neural delta and theta bands provides a potential mechanism to represent and integrate temporal information. Low-frequency neural entrainment is often studied using periodically changing stimuli and is analyzed in the frequency domain using the Fourier analysis. The Fourier analysis decomposes a periodic signal into harmonically related sinusoids. However, it is not intuitive how these harmonically related components are related to the response waveform. Here, we explain the interpretation of response harmonics, with a special focus on very low-frequency neural entrainment near 1 Hz. It is illustrated why neural responses repeating at f Hz do not necessarily generate any neural response at f Hz in the Fourier spectrum. A strong neural response at f Hz indicates that the time scales of the neural response waveform within each cycle match the time scales of the stimulus rhythm. Therefore, neural entrainment at very low frequency implies not only that the neural response repeats at f Hz but also that each period of the neural response is a slow wave matching the time scale of a f Hz sinusoid. PMID:27375465

  2. Ultra-low-noise EEG/MEG systems enable bimodal non-invasive detection of spike-like human somatosensory evoked responses at 1 kHz.

    PubMed

    Fedele, T; Scheer, H J; Burghoff, M; Curio, G; Körber, R

    2015-02-01

    Non-invasive EEG detection of very high frequency somatosensory evoked potentials featuring frequencies up to and above 1 kHz has been recently reported. Here, we establish the detectability of such components by combined low-noise EEG/MEG. We recorded SEP/SEF simultaneously using median nerve stimulation in five healthy human subjects inside an electromagnetically shielded room, combining a low-noise EEG custom-made amplifier (4.7 nV/√Hz) and a custom-made single-channel low-noise MEG (0.5 fT/√Hz @ 1 kHz). Both, low-noise EEG and MEG revealed three spectrally distinct and temporally overlapping evoked components: N20 (<100 Hz), sigma-burst (450-750 Hz), and kappa-burst (850-1200 Hz). The two recording modalities showed similar relative scaling of signal amplitude in all three frequencies domains (EEG [10 nV] ≅ MEG [1 fT]). Pronounced waveform (peak-by-peak) overlap of EEG and MEG signals is observed in the sigma band, whereas in the kappa band overlap was only partial. A decreasing signal-to-noise ratio (SNR; calculated for n = 12.000 averages) from sigma to kappa components characterizes both, electric and magnetic field recordings: Sigma-band SNR was 12.9  ±  5.5/19.8  ±  12.6 for EEG/MEG, and kappa-band SNR at 3.77  ±  0.8/4.5  ±  2.9. High-frequency performance of a tailor-made MEG matches closely with simultaneously recorded low-noise EEG for the non-invasive detection of somatosensory evoked activity at and above 1 kHz. Thus, future multi-channel dual-mode low-noise technology could offer complementary views for source reconstruction of the neural generators underlying such high-frequency responses, and render neural high-frequency processes related to multi-unit spike discharges accessible in non-invasive recordings.

  3. Training to improve manual control in 7-8 and 10-12 year old children: Training eliminates performance differences between ages.

    PubMed

    Snapp-Childs, Winona; Fath, Aaron J; Watson, Carol A; Flatters, Ian; Mon-Williams, Mark; Bingham, Geoffrey P

    2015-10-01

    Many children have difficulty producing movements well enough to improve in perceptuo-motor learning. We have developed a training method that supports active movement generation to allow improvement in a 3D tracing task requiring good compliance control. We previously tested 7-8 year old children who exhibited poor performance and performance differences before training. After training, performance was significantly improved and performance differences were eliminated. According to the Dynamic Systems Theory of development, appropriate support can enable younger children to acquire the ability to perform like older children. In the present study, we compared 7-8 and 10-12 year old school children and predicted that younger children would show reduced performance that was nonetheless amenable to training. Indeed, the pre-training performance of the 7-8 year olds was worse than that of the 10-12 year olds, but post-training performance was equally good for both groups. This was similar to previous results found using this training method for children with DCD and age-matched typically developing children. We also found in a previous study of 7-8 year old school children that training in the 3D tracing task transferred to a 2D drawing task. We now found similar transfer for the 10-12 year olds.

  4. New insights into the structure, assembly and biological roles of 10-12 nm connective tissue microfibrils from fibrillin-1 studies.

    PubMed

    Jensen, Sacha A; Handford, Penny A

    2016-04-01

    The 10-12 nm diameter microfibrils of the extracellular matrix (ECM) impart both structural and regulatory properties to load-bearing connective tissues. The main protein component is the calcium-dependent glycoprotein fibrillin, which assembles into microfibrils at the cell surface in a highly regulated process involving specific proteolysis, multimerization and glycosaminoglycan interactions. In higher metazoans, microfibrils act as a framework for elastin deposition and modification, resulting in the formation of elastic fibres, but they can also occur in elastin-free tissues where they perform structural roles. Fibrillin microfibrils are further engaged in a number of cell matrix interactions such as with integrins, bone morphogenetic proteins (BMPs) and the large latent complex of transforming growth factor-β (TGFβ). Fibrillin-1 (FBN1) mutations are associated with a range of heritable connective disorders, including Marfan syndrome (MFS) and the acromelic dysplasias, suggesting that the roles of 10-12 nm diameter microfibrils are pleiotropic. In recent years the use of molecular, cellular and whole-organism studies has revealed that the microfibril is not just a structural component of the ECM, but through its network of cell and matrix interactions it can exert profound regulatory effects on cell function. In this review we assess what is known about the molecular properties of fibrillin that enable it to assemble into the 10-12 nm diameter microfibril and perform such diverse roles. PMID:27026396

  5. New insights into the structure, assembly and biological roles of 10-12 nm connective tissue microfibrils from fibrillin-1 studies.

    PubMed

    Jensen, Sacha A; Handford, Penny A

    2016-04-01

    The 10-12 nm diameter microfibrils of the extracellular matrix (ECM) impart both structural and regulatory properties to load-bearing connective tissues. The main protein component is the calcium-dependent glycoprotein fibrillin, which assembles into microfibrils at the cell surface in a highly regulated process involving specific proteolysis, multimerization and glycosaminoglycan interactions. In higher metazoans, microfibrils act as a framework for elastin deposition and modification, resulting in the formation of elastic fibres, but they can also occur in elastin-free tissues where they perform structural roles. Fibrillin microfibrils are further engaged in a number of cell matrix interactions such as with integrins, bone morphogenetic proteins (BMPs) and the large latent complex of transforming growth factor-β (TGFβ). Fibrillin-1 (FBN1) mutations are associated with a range of heritable connective disorders, including Marfan syndrome (MFS) and the acromelic dysplasias, suggesting that the roles of 10-12 nm diameter microfibrils are pleiotropic. In recent years the use of molecular, cellular and whole-organism studies has revealed that the microfibril is not just a structural component of the ECM, but through its network of cell and matrix interactions it can exert profound regulatory effects on cell function. In this review we assess what is known about the molecular properties of fibrillin that enable it to assemble into the 10-12 nm diameter microfibril and perform such diverse roles.

  6. On the Nature of the mHz X-Ray QPOs from ULX M82 X-1: Evidence for Timing-Spectral (anti) Correlation

    NASA Technical Reports Server (NTRS)

    Pasham, Dheeraj R.; Strohmayer, Tod E.

    2013-01-01

    Using all the archival XMM-Newton X-ray (3-10 keV) observations of the ultraluminous X-ray source (ULX) M82 X-1 we searched for a correlation between its variable mHz quasi-periodic oscillation (QPO) frequency and its energy spectral power-law index. These quantities are known to correlate in stellar mass black holes (StMBHs) exhibiting Type-C QPOs (approx 0.2-15 Hz). The detection of such a correlation would strengthen the identification of its mHz QPOs as Type-C and enable a more reliable mass estimate by scaling its QPO frequencies to those of Type-C QPOs in StMBHs of known mass. We resolved the count rates of M82 X-1 and a nearby bright ULX (source 5/X42.3+59) through surface brightness modeling and identify observations in which M82 X-1 was at least as bright as source 5. Using only those observations, we detect QPOs in the frequency range of 36-210 mHz during which the energy spectral power-law index varied from 1.7-2.2. Interestingly, we find evidence for an anti-correlation (Pearsons correlation coefficient = -0.95) between the power-law index and the QPO centroid frequency. While such an anti-correlation is observed in StMBHs at high Type-C QPO frequencies (approx 5-15 Hz), the frequency range over which it holds in StMBHs is significantly smaller (factor of approx 1.5-3) than the QPO range reported here from M82 X-1 (factor of 6). However, it remains possible that contamination from source 5 can bias our result. Joint Chandra/XMM-Newton observations in the future can resolve this problem and confirm the timing-spectral anti-correlation reported here.

  7. Frequency noise induced by fiber perturbations in a fiber-linked stabilized laser

    NASA Technical Reports Server (NTRS)

    Pang, YI; Hamilton, Jeffrey J.; Richard, Jean-Paul

    1992-01-01

    The effects of acoustic perturbations on an optical fiber that links a stabilized laser to its reference cavity are studied. An extrapolation indicates that 69 dB of acoustic noise impinging on a 1-m segment of the 10-m fiber contribute frequency noise at the level of 1 Hz/(Hz)1/2 in the 1100-2100-Hz band.

  8. An ultralow noise preamplifier for low frequency noise measurements.

    PubMed

    Cannatà, Gianluca; Scandurra, Graziella; Ciofi, Carmine

    2009-11-01

    Low frequency noise measurements are among the most sensitive tools for the investigation of the quality and of the reliability of semiconductor devices. The sensitivity that can be obtained depends on the background noise of the low noise preamplifier coupled to the device under test (DUT) that, at very low frequencies, is dominated by flicker noise. The low frequency noise produced by the DUT, on the other end, is very often the most interesting signal to be detected and analyzed. In this work we propose a very simple topology for the realization of a general purpose low noise preamplifier whose noise performances, at very low frequencies (below 10 Hz), are significantly better than those that can be obtained by the most popular commercial instrumentation. Indeed, a gain of 80 dB with a pass band extending from a few tens of mHz up to a few kHz with an equivalent input voltage noise as low as 14 nV/square root(Hz) (100 mHz), 1.4 nV/square root(Hz) (1 Hz), 1.0 nV/square root(Hz) (10 Hz), and 0.8 nV/square root(Hz) (1 kHz) are consistently obtained by using quite standard electronic components and with no need for trimming and/or calibration steps. Moreover, the junction field-effect transistor input stage of the amplifier is characterized by an equivalent input current noise below 4 fA/square root(Hz) in the entire bandwidth, resulting in negligible background noise degradation for DUT impedances in excess of 100 kohms. PMID:19947746

  9. High-frequency electroacupuncture evidently reinforces hippocampal synaptic transmission in Alzheimer's disease rats

    PubMed Central

    Li, Wei; Kong, Li-hong; Wang, Hui; Shen, Feng; Wang, Ya-wen; Zhou, Hua; Sun, Guo-jie

    2016-01-01

    The frequency range of electroacupuncture in treatment of Alzheimer's disease in rats is commonly 2–5 Hz (low frequency) and 50–100 Hz (high frequency). We established a rat model of Alzheimer's disease by injecting β-amyloid 1–42 (Aβ1–42) into the bilateral hippocampal dentate gyrus to verify which frequency may be better suited in treatment. Electroacupuncture at 2 Hz or 50 Hz was used to stimulate Baihui (DU20) and Shenshu (BL23) acupoints. The water maze test and electrophysiological studies demonstrated that spatial memory ability was apparently improved, and the ranges of long-term potentiation and long-term depression were increased in Alzheimer's disease rats after electroacupuncture treatment. Moreover, the effects of electroacupuncture at 50 Hz were better than that at 2 Hz. These findings suggest that high-frequency electroacupuncture may enhance hippocampal synaptic transmission and potentially improve memory disorders in Alzheimer's disease rats. PMID:27335565

  10. development of a medium repetition rate (10 Hz - 500 Hz) diode pumped laser transmitter for airborne scanning altimetry

    NASA Technical Reports Server (NTRS)

    Coyle, D. Barry; Lindauer, Steven J., II; Kay, Richard B.

    1998-01-01

    Since the late 1980's, NASA has developed several small, all-solid state lasers of low repetition rates for use as transmitters in prototype LIDAR and raster scanned altimetry retrieval systems. Our early laser transmitters were developed for high resolution airborne altimetry which employed cavity dumping techniques to produce a pulse shape with a 1 ns rise time. The first such laser was the SUMR (Sub-millimeter resolution) transmitter which used a side pumped, D-shaped half-rod of Nd:YAG for the oscillator active media and produced approximately 3 ns pulses of 100 micro-J energy at a 40 Hz repetition rate. (Coyle and Blair, 1993; Coyle et al., 1995) After several upgrades to improve rep rate and pulse energy, the final version produced 1.2 mJ pulses at 120 Hz with a 3.7 ns pulse width. The laser has become known as SPLT (Sharp Pulsed Laser Transmitter), and has flown successfully on a variety of airborne altimetry missions. (Coyle and Blair, 1995; Blair et al., 1994) From building these systems, we have accrued valuable experience in delivering field-deployable lasers and have become aware of the advantages and disadvantages of employing new technologies. For example, even though the laser's main operating environment is in a "cold" aircraft during flight, the laser must still operate in very warm temperatures. This is important if the mission is based in the desert or a tropical climate since ground calibration data from stationary targets must be gathered before and after each data flight. Because conductive cooling is much more convenient than closed loop water flow, achieving the highest possible laser efficiency is becoming a high priority when designing a flight laser. This is especially true for lasers with higher pulse energies and repetition rates which are needed for high altitude scanning altimeters and LIDARs.

  11. Frequency division using a micromechanical resonance cascade

    SciTech Connect

    Qalandar, K. R. Gibson, B.; Sharma, M.; Ma, A.; Turner, K. L.; Strachan, B. S.; Shaw, S. W.

    2014-12-15

    A coupled micromechanical resonator array demonstrates a mechanical realization of multi-stage frequency division. The mechanical structure consists of a set of N sequentially perpendicular microbeams that are connected by relatively weak elastic elements such that the system vibration modes are localized to individual microbeams and have natural frequencies with ratios close to 1:2:⋯:2{sup N}. Conservative (passive) nonlinear inter-modal coupling provides the required energy transfer between modes and is achieved by finite deformation kinematics. When the highest frequency beam is excited, this arrangement promotes a cascade of subharmonic resonances that achieve frequency division of 2{sup j} at microbeam j for j = 1, …, N. Results are shown for a capacitively driven three-stage divider in which an input signal of 824 kHz is passively divided through three modal stages, producing signals at 412 kHz, 206 kHz, and 103 kHz. The system modes are characterized and used to delineate the range of AC input voltages and frequencies over which the cascade occurs. This narrow band frequency divider has simple design rules that are scalable to higher frequencies and can be extended to a larger number of modal stages.

  12. A variable-frequency local oscillator for the frequency-hopping technique

    NASA Technical Reports Server (NTRS)

    Stitt, G. R.; Johnson, L. J.

    1986-01-01

    The frequency hopping technique described elsewhere requires the use of a local oscillator whose output frequency may be rapidly and accurately changed by a fixed frequency increment. Such a device, capable of producing 16 different frequencies separated by 50 kHz over the range of 35.02 to 35.77 MHz, has been built for the Urbana MST (mesosphere stratosphere troposphere) radar facility. The design and construction of that device is described and illustrated.

  13. The Effect of the 226-Hz Probe Level on Contralateral Acoustic Stapedius Reflex Thresholds

    ERIC Educational Resources Information Center

    Day, Jessica E.; Feeney, M. Patrick

    2008-01-01

    Purpose: The purpose of this study was to examine the effect of the 226-Hz probe level on the acoustic stapedius reflex threshold. Method: Contralateral reflex thresholds for a 1000-Hz pure-tone stimulus were obtained from 40 young adults with normal hearing using an experimental system at four 226-Hz probe levels (70, 75, 80, and 85 dB SPL) with…

  14. 47 CFR 15.221 - Operation in the band 525-1705 kHz.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 1 2011-10-01 2011-10-01 false Operation in the band 525-1705 kHz. 15.221... kHz. (a) Carrier current systems and transmitters employing a leaky coaxial cable as the radiating antenna may operate in the band 525-1705 kHz provided the field strength levels of the radiated...

  15. 47 CFR 80.147 - Watch on 2182 kHz.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Watch on 2182 kHz. 80.147 Section 80.147 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES STATIONS IN THE... 2182 kHz. Ship stations must maintain a watch on 2182 kHz as prescribed by § 80.304....

  16. 47 CFR 15.221 - Operation in the band 525-1705 kHz.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 1 2013-10-01 2013-10-01 false Operation in the band 525-1705 kHz. 15.221... kHz. (a) Carrier current systems and transmitters employing a leaky coaxial cable as the radiating antenna may operate in the band 525-1705 kHz provided the field strength levels of the radiated...

  17. 47 CFR 80.147 - Watch on 2182 kHz.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Watch on 2182 kHz. 80.147 Section 80.147 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES STATIONS IN THE... 2182 kHz. Ship stations must maintain a watch on 2182 kHz as prescribed by § 80.304....

  18. 47 CFR 80.147 - Watch on 2182 kHz.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Watch on 2182 kHz. 80.147 Section 80.147 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES STATIONS IN THE... 2182 kHz. Ship stations must maintain a watch on 2182 kHz as prescribed by § 80.304....

  19. 47 CFR 80.147 - Watch on 2182 kHz.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Watch on 2182 kHz. 80.147 Section 80.147 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES STATIONS IN THE... 2182 kHz. Ship stations must maintain a watch on 2182 kHz as prescribed by § 80.304....

  20. 47 CFR 15.221 - Operation in the band 525-1705 kHz.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 1 2012-10-01 2012-10-01 false Operation in the band 525-1705 kHz. 15.221... kHz. (a) Carrier current systems and transmitters employing a leaky coaxial cable as the radiating antenna may operate in the band 525-1705 kHz provided the field strength levels of the radiated...

  1. 47 CFR 15.221 - Operation in the band 525-1705 kHz.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 1 2014-10-01 2014-10-01 false Operation in the band 525-1705 kHz. 15.221... kHz. (a) Carrier current systems and transmitters employing a leaky coaxial cable as the radiating antenna may operate in the band 525-1705 kHz provided the field strength levels of the radiated...

  2. 47 CFR 15.221 - Operation in the band 525-1705 kHz.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false Operation in the band 525-1705 kHz. 15.221... kHz. (a) Carrier current systems and transmitters employing a leaky coaxial cable as the radiating antenna may operate in the band 525-1705 kHz provided the field strength levels of the radiated...

  3. 47 CFR 80.147 - Watch on 2182 kHz.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Watch on 2182 kHz. 80.147 Section 80.147 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES STATIONS IN THE... 2182 kHz. Ship stations must maintain a watch on 2182 kHz as prescribed by § 80.304....

  4. Cardiovascular rhythms in the 0.15-Hz band: common origin of identical phenomena in man and dog in the reticular formation of the brain stem?

    PubMed

    Perlitz, Volker; Lambertz, Manfred; Cotuk, Birol; Grebe, Reinhard; Vandenhouten, Ralf; Flatten, Guido; Petzold, Ernst Richard; Schmid-Schönbein, Holger; Langhorst, Peter

    2004-09-01

    Selected examples from experiments in humans and dogs with time series of reticular neurons, respiration, arterial blood pressure and cutaneous forehead blood content fluctuations were analysed using multiscaled time-frequency distribution, post-event-scan and pointwise transinformation. We found in both experiments a "0.15-Hz rhythm" exhibiting periods of spindle waves (increasing and decreasing amplitudes), phase synchronized with respiration at 1:2 and 1:1 integer number ratios. At times of wave-epochs and n:m phase synchronization, the 0.15-Hz rhythm appeared in heart rate and arterial blood pressure. As phase synchronization of the 0.15-Hz rhythm with respiration was established at a 1:1 integer number ratio, all cardiovascular-respiratory oscillations were synchronized at 0.15 Hz. Analysis of a canine experiment supplied evidence that the emergence of the 0.15-Hz rhythm and n:m phase synchronization appears to result from a decline in the level of the general activity of the organism associated with a decline in the level of activity of reticular neurons in the lower brainstem network. These findings corroborate the notion of the 0.15-Hz rhythm as a marker of the "trophotropic mode of operation" first introduced by W.R. Hess. PMID:15138824

  5. Cardiovascular rhythms in the 0.15-Hz band: common origin of identical phenomena in man and dog in the reticular formation of the brain stem?

    PubMed

    Perlitz, Volker; Lambertz, Manfred; Cotuk, Birol; Grebe, Reinhard; Vandenhouten, Ralf; Flatten, Guido; Petzold, Ernst Richard; Schmid-Schönbein, Holger; Langhorst, Peter

    2004-09-01

    Selected examples from experiments in humans and dogs with time series of reticular neurons, respiration, arterial blood pressure and cutaneous forehead blood content fluctuations were analysed using multiscaled time-frequency distribution, post-event-scan and pointwise transinformation. We found in both experiments a "0.15-Hz rhythm" exhibiting periods of spindle waves (increasing and decreasing amplitudes), phase synchronized with respiration at 1:2 and 1:1 integer number ratios. At times of wave-epochs and n:m phase synchronization, the 0.15-Hz rhythm appeared in heart rate and arterial blood pressure. As phase synchronization of the 0.15-Hz rhythm with respiration was established at a 1:1 integer number ratio, all cardiovascular-respiratory oscillations were synchronized at 0.15 Hz. Analysis of a canine experiment supplied evidence that the emergence of the 0.15-Hz rhythm and n:m phase synchronization appears to result from a decline in the level of the general activity of the organism associated with a decline in the level of activity of reticular neurons in the lower brainstem network. These findings corroborate the notion of the 0.15-Hz rhythm as a marker of the "trophotropic mode of operation" first introduced by W.R. Hess.

  6. Low-frequency ac electroporation shows strong frequency dependence and yields comparable transfection results to dc electroporation.

    PubMed

    Zhan, Yihong; Cao, Zhenning; Bao, Ning; Li, Jianbo; Wang, Jun; Geng, Tao; Lin, Hao; Lu, Chang

    2012-06-28

    Conventional electroporation has been conducted by employing short direct current (dc) pulses for delivery of macromolecules such as DNA into cells. The use of alternating current (ac) field for electroporation has mostly been explored in the frequency range of 10kHz-1MHz. Based on Schwan equation, it was thought that with low ac frequencies (10Hz-10kHz), the transmembrane potential does not vary with the frequency. In this report, we utilized a flow-through electroporation technique that employed continuous 10Hz-10kHz ac field (based on either sine waves or square waves) for electroporation of cells with defined duration and intensity. Our results reveal that electropermeabilization becomes weaker with increased frequency in this range. In contrast, transfection efficiency with DNA reaches its maximum at medium frequencies (100-1000Hz) in the range. We postulate that the relationship between the transfection efficiency and the ac frequency is determined by combined effects from electrophoretic movement of DNA in the ac field, dependence of the DNA/membrane interaction on the ac frequency, and variation of transfection under different electropermeabilization intensities. The fact that ac electroporation in this frequency range yields high efficiency for transfection (up to ~71% for Chinese hamster ovary cells) and permeabilization suggests its potential for gene delivery.

  7. Cardiovascular response of rats exposed to 60-Hz electric fields

    SciTech Connect

    Hilton, D.I.; Phillips, R.D.

    1980-01-01

    Recently, it has been reported that exposure to high-strength electric fields can influence electrocardiogram (ECG) patterns, heart rates, and blood pressures in various species of animals. Our studies were designed to evaluate these reported effects and to help clarify some of the disagreement present in the literature. Various cardiovascular variables were measured in Sprague-Dawley rats exposed or sham-exposed to 60-Hz electric fields at 80 to 100 kV/m for periods up to four months. No significant differences in heart rates, ECG patterns, blood pressures, or vascular reactivity were observed between exposed and sham-exposed rats after 8 hours, 40 hours, 1 month, or 4 months of exposure. Our studies cannot be directly compared to the work of other investigators because of differences in animal species and electric-field characteristics. However, our failure to detect any cardiovascular changes may have been the result of (1) eliminating secondary field effects such as shocks, audible noise, corona, and ozone; (2) minimizing steady-state microcurrents between the mouth of the animal and watering devices; and (3) minimizing electric-field-induced vibration of the electrodes and animal cages.

  8. A wide range sigma—delta fractional-N frequency synthesizer with adaptive frequency calibration

    NASA Astrophysics Data System (ADS)

    Jianjun, Wei; Hanjun, Jiang; Lingwei, Zhang; Jingjing, Dong; Fule, Li; Zhihua, Wang; Chun, Zhang

    2013-06-01

    A wide range fractional-N frequency synthesizer in 0.18 μm RF CMOS technology is implemented. A switched-capacitors bank LC-tank VCO and an adaptive frequency calibration technique are used to expand the frequency range. A 16-bit third-order sigma—delta modulator with dither is used to randomize the fractional spur. The active area is 0.6 mm2. The experimental results show the proposed frequency synthesizer consumes 4.3 mA from a single 1.8 V supply voltage except for buffers. The frequency range is 1.44-2.11 GHz and the frequency resolution is less than 0.4 kHz. The phase noise is -94 dBc/Hz @ 100 kHz and -121 dBc/Hz @ 1 MHz at the output of the prescaler with a loop bandwidth of approximately 120 kHz. The performance meets the requirements for the multi-band and multi-mode transceiver applications.

  9. Compact dual-frequency fiber laser accelerometer with sub-μg resolution

    NASA Astrophysics Data System (ADS)

    Cao, Qian; Jin, Long; Liang, Yizhi; Cheng, Linghao; Guan, Bai-Ou

    2016-06-01

    We demonstrate a compact and high-resolution dual-polarization fiber laser accelerometer. A spring-mass like scheme is constructed by fixing a 10-gram proof mass on the laser cavity to transduce applied vibration into beat-frequency change. The loading is located at the intensity maximum of intracavity light to maximize the optical response. The detection limit reaches 107 ng/Hz1/2 at 200 Hz. The working bandwidth ranges from 60 Hz to 600 Hz.

  10. Comparison of real beat-to-beat signals with commercially available 4 Hz sampling on the evaluation of foetal heart rate variability.

    PubMed

    Gonçalves, Hernâni; Costa, Antónia; Ayres-de-Campos, Diogo; Costa-Santos, Cristina; Rocha, Ana Paula; Bernardes, João

    2013-06-01

    Evaluation of foetal heart rate (FHR) variability is an essential part of foetal monitoring, but a precise quantification of this parameter depends on the quality of the signal. In this study, we compared real FHR beat-to-beat signals with 4 Hz sampling provided by commercial foetal monitors on linear and nonlinear indices and analysed their clinical implications. Simultaneous acquisition of beat-to-beat signals and their 4 Hz sampling rate counterparts was performed using a scalp electrode, during the last hour of labour in 21 fetuses born with an umbilical artery blood (UAB) pH ≥ 7.20 and 6 born with an UAB pH < 7.20. For each case, the first and last 10 min segments were analysed, using time and frequency domain linear, and nonlinear FHR indices, namely mean FHR, low frequency, high frequency, approximate, sample and multiscale entropy. Significant differences in variability indices were found between beat-to-beat and 4 Hz sampled signals, with a lesser effect seen with 2 Hz sampling. These differences did not affect physiological changes observed during labour progression, such as decreased entropy and linear time domain indices, and increased frequency domain indices. However, significant differences were found in the discrimination between fetuses born with different UAB pHs, with beat-to-beat sampling providing better results in linear indices and 4 Hz sampling better results in entropy indices. In conclusion, different FHR sampling frequencies can significantly affect the quantification of variability indices. This needs to be taken into account in the interpretation of FHR variability and in the development of new equipment.

  11. The rat suprachiasmatic nucleus: the master clock ticks at 30 Hz

    PubMed Central

    Tsuji, Takahiro; Tsuji, Chiharu; Ludwig, Mike

    2016-01-01

    Key points Light‐responsive neurones in the rat suprachiasmatic nucleus discharge with a harmonic distribution of interspike intervals, whereas unresponsive neurones seldom do.This harmonic patterning has a fundamental frequency of close to 30 Hz, and is the same in light‐on cells as in light‐off cells, and is unaffected by exposure to light.Light‐on cells are more active than light‐off cells in both subjective day and subjective night, and both light‐on cells and light‐off cells respond more strongly to changes in light intensity during the subjective night than during the subjective day.Paired recordings indicate that the discharge of adjacent light‐responsive cells is very tightly synchronized.The gap junction inhibitor carbenoxolone increases the spontaneous activity of suprachiasmatic nucleus neurones but does not block the harmonic discharge patterning. Abstract The suprachiasmatic nucleus (SCN) of the hypothalamus has an essential role in orchestrating circadian rhythms of behaviour and physiology. In the present study, we recorded from single SCN neurons in urethane‐anaesthetized rats, categorized them by the statistical features of their electrical activity and by their responses to light, and examined how activity in the light phase differs from activity in the dark phase. We classified cells as light‐on cells or light‐off cells according to how their firing rate changed in acute response to light, or as non‐responsive cells. In both sets of light‐responsive neurons, responses to light were stronger at subjective night than in subjective day. Neuronal firing patterns were analysed by constructing hazard functions from interspike interval data. For most light‐responsive cells, the hazard functions showed a multimodal distribution, with a harmonic sequence of modes, indicating that spike activity was driven by an oscillatory input with a fundamental frequency of close to 30 Hz; this harmonic pattern was rarely seen in non

  12. A 2.2-Hz modulation of auroral electrons imposed at the geomagnetic equator

    NASA Astrophysics Data System (ADS)

    Lepine, D. R.; Bryant, D. A.; Hall, D. S.

    1980-07-01

    The direct observation of 2.2-Hz oscillations in the intensities of 4-25 keV electrons producing a pulsating aurora is reported. Electrons were measured by a Petrel sounding rocket launched from Kiruna, Sweden in conjunction with measurements made by the geomagnetically conjugate GEOS 2 satellite. Measured precipitated energy flux variations only amounted to 3% of the energy flux at pulsation maximum, and thus do not permit the confirmation of particle modulations as the source of optical brightness modulations. The oscillations, like the previously observed 1-20 sec pulsations, are found to exhibit a marked velocity dispersion, implying an equatorial origin for both forms of modulation. A comparison of the rocket results with GEOS 2 measurements indicates VLF hiss emissions to be modulated at a frequency close to that of electron intensity oscillations, however isotropic angular distributions observed suggest that low-frequency micropulsations cannot cause auroral pulsations by modulating whistler-mode wave amplitudes which induce variations in the rate of pitch-angle scattering of electrons from the magnetosphere.

  13. Task-sensitive reconfiguration of corticocortical 6-20 Hz oscillatory coherence in naturalistic human performance.

    PubMed

    Saarinen, Timo; Jalava, Antti; Kujala, Jan; Stevenson, Claire; Salmelin, Riitta

    2015-07-01

    Electrophysiological oscillatory coherence between brain regions has been proposed to facilitate functional long-range connectivity within neurocognitive networks. This notion is supported by intracortical recordings of coherence in singled-out corticocortical connections in the primate cortex. However, the manner in which this operational principle manifests in the task-sensitive connectivity that supports human naturalistic performance remains undercharacterized. Here, we demonstrate task-sensitive reconfiguration of global patterns of coherent connectivity in association with a set of easier and more demanding naturalistic tasks, ranging from picture comparison to speech comprehension and object manipulation. Based on whole-cortex neuromagnetic recording in healthy behaving individuals, the task-sensitive component of long-range corticocortical coherence was mapped at spectrally narrow-band oscillatory frequencies between 6 and 20 Hz (theta to alpha and low-beta bands). This data-driven cortical mapping unveiled markedly distinct and topologically task-relevant spatiospectral connectivity patterns for the different tasks. The results demonstrate semistable oscillatory states relevant for neurocognitive processing. The present findings decisively link human behavior to corticocortical coherence at oscillatory frequencies that are widely thought to convey long-range, feedback-type neural interaction in cortical functional networks.

  14. Cavity-dumped Yb:YAG ceramic in the 20  W, 12  mJ range at 6.7  ns operating from 20  Hz to 5  kHz with fluorescence feedback control.

    PubMed

    Fries, Christian; Weitz, Marco; Theobald, Christian; Löwis Of Menar, Patric V; Bartschke, Jürgen; L'huillier, Johannes A

    2016-08-20

    Increasing data acquisition rates in metrology applications based on optical parametric oscillators (OPOs) can accelerate measurement processes. To achieve this, flash-lamp systems with low pulse repetition frequencies of 10-100 Hz used as a pump source for the OPOs could be replaced by diode-pumped solid-state lasers in the kHz range. We demonstrate a 969 nm pumped Yb:YAG ceramic laser yielding 21.6 W output power, 12.5 mJ pulse energy, and excellent beam quality. Fluorescence feedback control, developed from gain dynamics simulations in two operating regimes, allows stable operation at 6.7 ns from 20 to 5000 Hz. Third harmonic generation to 343 nm yields 3.24 W at 2 kHz. The system provides constant pulse duration in a huge repetition rate interval, which is beneficial for pump sources for future metrology devices. PMID:27556969

  15. Deep frequency modulation interferometry.

    PubMed

    Gerberding, Oliver

    2015-06-01

    Laser interferometry with pm/Hz precision and multi-fringe dynamic range at low frequencies is a core technology to measure the motion of various objects (test masses) in space and ground based experiments for gravitational wave detection and geodesy. Even though available interferometer schemes are well understood, their construction remains complex, often involving, for example, the need to build quasi-monolithic optical benches with dozens of components. In recent years techniques have been investigated that aim to reduce this complexity by combining phase modulation techniques with sophisticated digital readout algorithms. This article presents a new scheme that uses strong laser frequency modulations in combination with the deep phase modulation readout algorithm to construct simpler and easily scalable interferometers. PMID:26072834

  16. Deep frequency modulation interferometry.

    PubMed

    Gerberding, Oliver

    2015-06-01

    Laser interferometry with pm/Hz precision and multi-fringe dynamic range at low frequencies is a core technology to measure the motion of various objects (test masses) in space and ground based experiments for gravitational wave detection and geodesy. Even though available interferometer schemes are well understood, their construction remains complex, often involving, for example, the need to build quasi-monolithic optical benches with dozens of components. In recent years techniques have been investigated that aim to reduce this complexity by combining phase modulation techniques with sophisticated digital readout algorithms. This article presents a new scheme that uses strong laser frequency modulations in combination with the deep phase modulation readout algorithm to construct simpler and easily scalable interferometers.

  17. Different frequencies should be prescribed for different high frequency chest compression machines.

    PubMed

    Milla, Carlos E; Hansen, Leland G; Warwick, Warren J

    2006-01-01

    High frequency chest compression (HFCC) is used for treatment and prevention of the lung diseases characterized by impaired mucus clearance and/or cough, where patients are at risk for acquiring acute bronchitis or pneumonia. The HFCC treatment frequencies may be prescribed according to the manufacturers' generic guidelines or may be determined for each individual patient by a "tuning" method that measures, at the mouth, the air volume displacement and the associated airflows produced at each frequency. Tuning is performed while the patient is breathing normally during the HFCC system operation. After measurements for several breaths at one frequency have been collected, the program randomly selects and measures another frequency until the entire frequency range of the machine being tuned has been sampled. Frequencies range from 6 to 21 Hz for the sine waveform machines and from 6 to 25 Hz for the square waveform machines. Each group of flow signals is digitized and analyzed by the program. For each frequency, the HFCC flow velocities and volumes are computed and averaged. These average flows and volumes are rank ordered; the three frequencies with the highest flows and the three frequencies producing the largest volumes are selected for prescription. If the same frequency is selected as one of the three best frequencies for both flow and volume, the next ranked frequency is selected randomly for flow or volume. Significant differences exist between patients and HFCC machines. In a series of 100 cystic fibrosis (CF) patients with varying degrees of lung disease, we found that the best-ranked frequencies varied from patient to patient and did not correlate with patients' age, gender, height, weight, or spirometry parameters. With the sine waveform, the highest HFCC airflows were between 13 and 20 Hz 82% of the time and the largest HFCC volumes were between 6 and 10 Hz 83% of the time. With the square waveform, both the highest average HFCC flow rates and the largest

  18. Acute exposure to 50-Hz magnetic fields increases interleukin-6 in young healthy men.

    PubMed

    Selmaoui, Brahim; Lambrozo, Jacques; Sackett-Lundeen, Linda; Haus, Erhard; Touitou, Yvan

    2011-12-01

    Some epidemiologic studies have suggested that extremely low frequency magnetic fields might affect human health and, in particular, that the incidence of certain types of cancer might increase among individuals living or working in environments exposed to such fields. This study is part of a broad study we conducted in humans. The study presented here was designed to look for possible effects of acute exposure to 50-Hz magnetic fields (10 μT) on the interleukin 1 beta (IL-1β), interleukin 2 (IL-2), interleukin 6 (IL-6), interleukin-1 receptor antagonist (IL-1RA), and the interleukin-2 receptor (IL-2R) production. Thirty-two young men (20-30 years old) were divided into two groups (sham-exposed or control group and exposed group) of 16 subjects each. All subjects participated in two 24-h experiments to evaluate the effects of both continuous and intermittent (1 h "off" and 1 h "on" with the field switched "on" and "off" every 15 s) exposure to linearly polarized magnetic fields. The subjects were exposed to the magnetic field from 2300 to 0800 while recumbent. Blood samples were collected during each session at 11:00, 17:00, 22:00, 01:00, 04:00, 06:00, and 08:00. Results showed that exposure to 50-Hz magnetic fields (10 μT) significantly increases IL-6 when subjects were exposed to an intermittent magnetic field. However, no effect has been observed on interleukin IL-1β, IL-2, IL-1RA, and IL-2R.

  19. All-optical frequency and intensity noise suppression of single-frequency fiber laser.

    PubMed

    Li, Can; Xu, Shanhui; Huang, Xiang; Xiao, Yu; Feng, Zhouming; Yang, Changsheng; Zhou, Kaijun; Lin, Wei; Gan, Jiulin; Yang, Zhongmin

    2015-05-01

    An all-optical frequency and intensity noise suppression technique of a single-frequency fiber laser is demonstrated. By exploiting the recursive noise reduction effect of a semiconductor optical amplifier (SOA) in a self-injection locked fiber laser, the frequency and intensity noise of the laser are remarkably suppressed in a significantly wide frequency range. In addition to the linewidth suppression from 3.5 kHz to 700 Hz, the frequency noise has been reduced by ∼25  dB. After suppression, the relative intensity noise (RIN) is within 5 dB of the shot noise limit at frequencies from 1.5 to 3 MHz, and the frequency range of the suppression reaches about 30 MHz. The relaxation oscillation peak is observed to shift to lower frequencies and is reduced by about 35 dB from -90  dB/Hz to -125  dB/Hz. It is believed that the achieved low noise makes the fiber laser a promising candidate in applications such as ultra-long haul coherent optical communication and LIDAR.

  20. Cavitation thresholds of contrast agents in an in vitro human clot model exposed to 120-kHz ultrasound

    PubMed Central

    Gruber, Matthew J.; Bader, Kenneth B.; Holland, Christy K.

    2014-01-01

    Ultrasound contrast agents (UCAs) can be employed to nucleate cavitation to achieve desired bioeffects, such as thrombolysis, in therapeutic ultrasound applications. Effective methods of enhancing thrombolysis with ultrasound have been examined at low frequencies (<1 MHz) and low amplitudes (<0.5 MPa). The objective of this study was to determine cavitation thresholds for two UCAs exposed to 120-kHz ultrasound. A commercial ultrasound contrast agent (Definity®) and echogenic liposomes were investigated to determine the acoustic pressure threshold for ultraharmonic (UH) and broadband (BB) generation using an in vitro flow model perfused with human plasma. Cavitation emissions were detected using two passive receivers over a narrow frequency bandwidth (540–900 kHz) and a broad frequency bandwidth (0.54–1.74 MHz). UH and BB cavitation thresholds occurred at the same acoustic pressure (0.3 ± 0.1 MPa, peak to peak) and were found to depend on the sensitivity of the cavitation detector but not on the nucleating contrast agent or ultrasound duty cycle. PMID:25234874

  1. Study of the 20,22Ne+20,22Ne and 10,12,13,14,15C+12C Fusion Reactions with MUSIC

    NASA Astrophysics Data System (ADS)

    Avila, M. L.; Rehm, K. E.; Almaraz-Calderon, S.; Carnelli, P. F. F.; DiGiovine, B.; Esbensen, H.; Hoffman, C. R.; Jiang, C. L.; Kay, B. P.; Lai, J.; Nusair, O.; Pardo, R. C.; Santiago-Gonzalez, D.; Talwar, R.; Ugalde, C.

    2016-05-01

    A highly efficient MUlti-Sampling Ionization Chamber (MUSIC) detector has been developed for measurements of fusion reactions. A study of fusion cross sections in the 10,12,13,14,15C+12C and 20,22Ne+20,22Ne systems has been performed at ATLAS. Experimental results and comparison with theoretical predictions are presented. Furthermore, results of direct measurements of the 17O(α, n)20Ne, 23Ne(α, p)26Mg and 23Ne(α, n)26Al reactions will be discussed.

  2. Synthesis of novel 12-aryl-8,9,10,12-tetrahydrobenzo[a]xanthene-11-thiones and evaluation of their biocidal effects.

    PubMed

    Khurana, Jitender M; Magoo, Devanshi; Aggarwal, Komal; Aggarwal, Nisha; Kumar, Rajesh; Srivastava, Chitra

    2012-12-01

    Novel 12-aryl-8,9,10,12-tetrahydrobenzo[a]xanthene-11-thiones have been synthesized in high yields by treatment of the corresponding oxo analogs with Lawesson's reagent. The structure has been confirmed by X-ray analysis. The compounds were tested for in vitro antifungal activity against Rhizoctonia bataticola, Sclerotium rolfsii, Fusarium oxysporum and Alternaria porii. The compounds exhibited moderate to good activity against all pathogens. Insecticidal activity of these compounds against Spodoptera litura was observed to be comparable to commercial pyrethroid insecticide, cypermethrin. The urease inhibitory activity has also been studied. PMID:23153816

  3. Nonuniform High-Gamma (60–500 Hz) Power Changes Dissociate Cognitive Task and Anatomy in Human Cortex

    PubMed Central

    Gaona, Charles M.; Sharma, Mohit; Freudenburg, Zachary V.; Breshears, Jonathan D.; Bundy, David T.; Roland, Jarod; Barbour, Dennis L.; Schalk, Gerwin

    2011-01-01

    High-gamma-band (>60 Hz) power changes in cortical electrophysiology are a reliable indicator of focal, event-related cortical activity. Despite discoveries of oscillatory subthreshold and synchronous suprathreshold activity at the cellular level, there is an increasingly popular view that high-gamma-band amplitude changes recorded from cellular ensembles are the result of asynchronous firing activity that yields wideband and uniform power increases. Others have demonstrated independence of power changes in the low- and high-gamma bands, but to date, no studies have shown evidence of any such independence above 60 Hz. Based on nonuniformities in time-frequency analyses of electrocorticographic (ECoG) signals, we hypothesized that induced high-gamma-band (60–500 Hz) power changes are more heterogeneous than currently understood. Using single-word repetition tasks in six human subjects, we showed that functional responsiveness of different ECoG high-gamma sub-bands can discriminate cognitive task (e.g., hearing, reading, speaking) and cortical locations. Power changes in these sub-bands of the high-gamma range are consistently present within single trials and have statistically different time courses within the trial structure. Moreover, when consolidated across all subjects within three task-relevant anatomic regions (sensorimotor, Broca's area, and superior temporal gyrus), these behavior- and location-dependent power changes evidenced nonuniform trends across the population. Together, the independence and nonuniformity of power changes across a broad range of frequencies suggest that a new approach to evaluating high-gamma-band cortical activity is necessary. These findings show that in addition to time and location, frequency is another fundamental dimension of high-gamma dynamics. PMID:21307246

  4. Physics: Grades 10-12.

    ERIC Educational Resources Information Center

    Instructional Objectives Exchange, Los Angeles, CA.

    The physics objectives are geared to use in college preparatory, high school physics courses and are based on the three most common physics curricula: (1) Physical Science Study Committee (PSSC); (2) The Project Physics Course; and (3) Modern Physics by Dull, Metcalf, and Williams. Since many of the sample items can be answered in various ways,…

  5. Upper limit on a stochastic background of gravitational waves from seismic measurements in the range 0.05-1 Hz.

    PubMed

    Coughlin, Michael; Harms, Jan

    2014-03-14

    In this Letter, we present an upper limit of ΩGW<1.2×108 on an isotropic stochastic gravitational-wave (GW) background integrated over a year in the frequency range 0.05-1 Hz, which improves current upper limits from high-precision laboratory experiments by about 9 orders of magnitude. The limit is obtained using the response of Earth itself to GWs via a free-surface effect described more than 40 years ago by Dyson. The response was measured by a global network of broadband seismometers selected to maximize the sensitivity. PMID:24679277

  6. Upper limit on a stochastic background of gravitational waves from seismic measurements in the range 0.05-1 Hz.

    PubMed

    Coughlin, Michael; Harms, Jan

    2014-03-14

    In this Letter, we present an upper limit of ΩGW<1.2×108 on an isotropic stochastic gravitational-wave (GW) background integrated over a year in the frequency range 0.05-1 Hz, which improves current upper limits from high-precision laboratory experiments by about 9 orders of magnitude. The limit is obtained using the response of Earth itself to GWs via a free-surface effect described more than 40 years ago by Dyson. The response was measured by a global network of broadband seismometers selected to maximize the sensitivity.

  7. Efficient 1 kHz femtosecond optical parametric amplification in BiB(3)O(6) pumped at 800 nm.

    PubMed

    Ghotbi, Masood; Ebrahim-Zadeh, Majid; Petrov, Valentin; Tzankov, Pancho; Noack, Frank

    2006-10-30

    We demonstrate efficient operation of a tunable femtosecond optical parametric amplifier based on BiB(3)O(6) pumped at 800 nm by a 1 kHz Ti:sapphire regenerative amplifier. The idler wavelength coverage extends to beyond 3 mum and the pulse duration at this wavelength is of the order of 110 fs. This new nonlinear borate crystal offers exceptionally high nonlinearity, making it a very promising candidate for power scaling of such frequency converters in the near-IR.

  8. Frequency- and intensity-noise suppression in Yb3+-doped single-frequency fiber laser by a passive optical-feedback loop.

    PubMed

    Hou, Yubin; Zhang, Qian; Wang, Pu

    2016-06-13

    The frequency and intensity noise of an Yb3+-doped single-frequency distributed Bragg reflector (DBR) fiber laser are effectively reduced by a simple, passive optical-feedback loop (POFL), which consists of only two optical couplers. The feedback loop, which has resonance with the high reflective grating of the DBR laser and relative long optical path compared to the DBR cavity, results in narrower linewidth and lower relative intensity noise (RIN) in the feedback signal. The RIN of relaxation oscillation is reduced by 20dB from -99.9dB/Hz @ 993 kHz to -119.4dB/Hz @ 192 kHz, and the frequency noise was suppressed at frequencies higher than 1 kHz, with a maximum reduction of about 30 dB from 10 kHz to 100 kHz, which results in a spectral linewidth compression from 3.96 kHz to 540 Hz. Even after one fiber amplification stage, the noise did not increase significantly, and a spectral linewidth well below 1 kHz were also achieved at output power of 10W. PMID:27410318

  9. Instrument for determining the complex shear modulus of soft-tissue-like materials from 10 to 300 Hz

    PubMed Central

    Madsen, E L; Frank, G R; Hobson, M A; Lin-Gibson, S; Hall, T J; Jiang, J; Stiles, T A

    2010-01-01

    Accurate determination of the complex shear modulus of soft tissues and soft-tissue-like materials in the 10–300 Hz frequency range is very important to researchers in MR elastography and acoustic radiation force impulse (ARFI) imaging. A variety of instruments for making such measurements has been reported, but none of them is easily reproduced, and none have been tested to conform to causality via the Kramers–Kronig (K-K) relations. A promising linear oscillation instrument described in a previous brief report operates between 20 and 160 Hz, but results were not tested for conformity to the K-K relations. We have produced a similar instrument with our own version of the electronic components and have also accounted for instrumental effects on the data reduction, which is not addressed in the previous report. The improved instrument has been shown to conform to an accurate approximation of the K-K relations over the 10–300 Hz range. The K-K approximation is based on the Weichert mechanical circuit model. We also found that the sample thickness must be small enough to obtain agreement with a calibrated commercial rheometer. A complete description of the improved instrument is given, facilitating replication in other labs. PMID:18758002

  10. 20 kHz toluene planar laser-induced fluorescence imaging of a jet in nearly sonic crossflow

    NASA Astrophysics Data System (ADS)

    Miller, V. A.; Troutman, V. A.; Mungal, M. G.; Hanson, R. K.

    2014-10-01

    This manuscript describes continuous, high-repetition-rate (20 kHz) toluene planar laser-induced fluorescence (PLIF) imaging in an expansion tube impulse flow facility. Cinematographic image sequences are acquired that visualize an underexpanded jet of hydrogen in Mach 0.9 crossflow, a practical flow configuration relevant to aerospace propulsion systems. The freestream gas is nitrogen seeded with toluene; toluene broadly absorbs and fluoresces in the ultraviolet, and the relatively high quantum yield of toluene produces large signals and high signal-to-noise ratios. Toluene is excited using a commercially available, frequency-quadrupled (266 nm), high-repetition-rate (20 kHz), pulsed (0.8-0.9 mJ per pulse), diode-pumped solid-state Nd:YAG laser, and fluorescence is imaged with a high-repetition-rate intensifier and CMOS camera. The resulting PLIF movie and image sequences are presented, visualizing the jet start-up process and the dynamics of the jet in crossflow; the freestream duration and a measure of freestream momentum flux steadiness are also inferred. This work demonstrates progress toward continuous PLIF imaging of practical flow systems in impulse facilities at kHz acquisition rates using practical, turn-key, high-speed laser and imaging systems.

  11. High-anxiety rats are less sensitive to the rewarding affects of amphetamine on 50kHz USV.

    PubMed

    Lehner, Małgorzata H; Taracha, Ewa; Kaniuga, Ewelina; Wisłowska-Stanek, Aleksandra; Wróbel, Jacek; Sobolewska, Alicja; Turzyńska, Danuta; Skórzewska, Anna; Płaźnik, Adam

    2014-12-15

    This study assessed behaviour, as measured by 50kHz calls related to positive affect, in rats with different fear conditioned response strengths: low-anxiety rats (LR) and high-anxiety rats (HR), after amphetamine injection in a two-injection protocol (TIPS). The results showed that the first dose of amphetamine evoked similar behavioural effects in frequency-modulated (FM) 50kHz calls in the LR and HR groups. The second injection of amphetamine resulted in stronger FM 50kHz calls in LR compared with HR rats. The biochemical data ('ex vivo' analysis) showed that the LR rats had increased basal levels of dopamine in the amygdala, and increased homovanilic acid (HVA), dopamine's main metabolite, in the amygdala and prefrontal cortex compared with HR rats. The 'in vivo' analysis (microdialysis study) showed that the LR rats had increased HVA concentrations in the basolateral amygdala in response to an aversively conditioned context. Research has suggested that differences in dopaminergic system activity in the amygdala and prefrontal cortex may be one of the biological factors that underlie individual differences in response to fear stimuli, which may also affect the rewarding effects of amphetamine.

  12. About the p-mode frequency shifts in HD 49933

    NASA Astrophysics Data System (ADS)

    Salabert, D.; Régulo, C.; Ballot, J.; García, R. A.; Mathur, S.

    2011-06-01

    We study the frequency dependence of the frequency shifts of the low-degree p modes measured in the F5V star HD 49933, by analyzing the second run of observations collected by the CoRoT satellite. The 137-day light curve is divided into two subseries corresponding to periods of low and high stellar activity. The activity-frequency relationship is obtained independently from the analysis of the mode frequencies extracted by both a local and a global peak-fitting analyses, and from a cross-correlation technique in the frequency range between 1450 μHz and 2500 μHz. The three methods return consistent results. We show that the frequency shifts measured in HD 49933 present a frequency dependence with a clear increase with frequency, reaching a maximal shift of about 2 μHz around 2100 μHz. Similar variations are obtained between the l = 0 and l = 1 modes. At higher frequencies, the frequency shifts show indications of a downturn followed by an upturn, consistent between the l = 0 and 1 modes. We show that the frequency variation of the p-mode frequency shifts of the solar-like oscillating star HD 49933 has a comparable shape to the one observed in the Sun, which is understood to arise from changes in the outer layers due to its magnetic activity.

  13. 33 CFR 86.03 - Limits of fundamental frequencies.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Limits of fundamental frequencies... of fundamental frequencies. To ensure a wide variety of whistle characteristics, the fundamental frequency of a whistle shall be between the following limits: (a) 70-200 Hz, for a vessel 200 meters or...

  14. 33 CFR 86.03 - Limits of fundamental frequencies.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Limits of fundamental frequencies... of fundamental frequencies. To ensure a wide variety of whistle characteristics, the fundamental frequency of a whistle shall be between the following limits: (a) 70-200 Hz, for a vessel 200 meters or...

  15. 33 CFR 86.03 - Limits of fundamental frequencies.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Limits of fundamental frequencies... of fundamental frequencies. To ensure a wide variety of whistle characteristics, the fundamental frequency of a whistle shall be between the following limits: (a) 70-200 Hz, for a vessel 200 meters or...

  16. 47 CFR 80.143 - Required frequencies for radiotelephony.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Required frequencies for radiotelephony. 80.143... Stations § 80.143 Required frequencies for radiotelephony. (a) Except for compulsory vessels, each ship... emission on the frequency 2182 kHz. Ship stations are additionally authorized to receive and transmit...

  17. Preferred frequencies for three unconsolidated earth materials

    SciTech Connect

    Gilcrist, Laura E.; Baker, Gregory S.; Sen, Surajit

    2007-12-17

    Exploring near-surface mechanical wave propagation through cohesive and noncohesive soils is important for detecting buried objects (i.e., landmines and unexploded ordnance). Here, we determine that certain preferred frequencies travel through specific soils more efficiently. A controlled-frequency acoustic seismic source was developed to modulate the applied frequency and amplitude. Surface response due to continuous waves traveling through soils was recorded both instantaneously and after a finite load time. Preferred frequencies for sand, clay loam, and silt loam were measured to be 300-330, 100-140, and 140-260 Hz, respectively. Observed frequency shifts were dependent upon applied amplitude and load time.

  18. On-chip high sensitivity laser frequency sensing with Brillouin mutually-modulated cross-gain modulation.

    PubMed

    Gao, Feng; Pant, Ravi; Li, Enbang; Poulton, Christopher G; Choi, Duk-Yong; Madden, Stephen J; Luther-Davies, Barry; Eggleton, Benjamin J

    2013-04-01

    We report the first demonstration of a photonic-chip laser frequency sensor using Brillouin mutually-modulated cross-gain modulation (MMXGM). A large sensitivity (~9.5 mrad/kHz) of the modulation phase shift to probe carrier frequency is demonstrated at a modulation frequency of 50 kHz using Brillouin MMXGM in a ~7 cm long chalcogenide rib waveguide.

  19. Very Broadband Rayleigh-Wave Dispersion (0.06 - 60 Hz) and Shear-Wave Velocity Structure Under Yucca Flat, Nevada Test Site

    NASA Astrophysics Data System (ADS)

    Schramm, K. A.; Bilek, S. L.; Patton, H. J.; Abbott, R. E.; Stead, R.; Pancha, A.; White, R.

    2009-12-01

    Earth structure plays an important role in the generation of seismic waves for all sources. Nowhere is this more evident than at near-surface depths where man-made sources, such as explosions, are conducted. For example, short-period Rayleigh waves (Rg) are excited and propagate in the upper 2 km of Earth's crust. The importance of Rg in the generation of S waves from explosion sources through near-source scattering depends greatly on the shear-wave velocity structure at very shallow depths. Using three distinct datasets, we present a very broadband Rayleigh-wave phase velocity dispersion curve for the Yucca Flat (YF) region of the Nevada Test Site (NTS). The first dataset consists of waveforms of historic NTS explosions recorded on regional seismic networks and will provide information for the lowest frequencies (0.06-0.3 Hz). The second dataset is comprised of waveforms from a non-nuclear explosion on YF recorded at near-local distances and will be used for mid-range frequencies (0.2-1.5 Hz). The third dataset contains high-frequency waveforms recorded from refraction microtremor surveys on YF. This dataset provides information between 1.5 and 60 Hz. Initial results from the high frequency dataset indicate velocities range from 0.45-0.9 km/s at 1.5 Hz and 0.25-0.45 km/s at 60 Hz. The broadband nature of the dispersion curve will allow us to invert for the shear-wave velocity structure to 10 km depth, with focus on shallow depths where nuclear tests were conducted in the YF region. The velocity model will be used by researchers as a tool to aid the development of new explosion source models that incorporate shear wave generation. The new model can also be used to help improve regional distance yield estimation and source discrimination for small events.

  20. Electromagnetic radiation trapped in the magnetosphere above the plasma frequency

    NASA Technical Reports Server (NTRS)

    Gurnett, D. A.; Shaw, R. R.

    1973-01-01

    An electromagnetic noise band is frequently observed in the outer magnetosphere by the Imp 6 spacecraft at frequencies from about 5 to 20 kHz. This noise band generally extends throughout the region from near the plasmapause boundary to near the magnetopause boundary. The noise typically has a broadband field strength of about 5 microvolts/meter. The noise band often has a sharp lower cutoff frequency at about 5 to 10 kHz, and this cutoff has been identified as the local electron plasma frequency. Since the plasma frequency in the plasmasphere and solar wind is usually above 20 kHz, it is concluded that this noise must be trapped in the low-density region between the plasmapause and magnetopause boundaries. The noise bands often contain a harmonic frequency structure which suggests that the radiation is associated with harmonics of the electron cyclotron frequency.

  1. The effects of 1 Hz rTMS preconditioned by tDCS on gait kinematics in Parkinson's disease.

    PubMed

    von Papen, Mitra; Fisse, Mirabell; Sarfeld, Anna-Sophia; Fink, Gereon R; Nowak, Dennis A

    2014-07-01

    Hypokinetic gait is a common and very disabling symptom of Parkinson's disease (PD). Repetitive transcranial magnetic stimulation (rTMS) over the motor cortex has been used with variable effectiveness to treat hypokinesia in PD. Preconditioning rTMS by transcranial direct current stimulation (tDCS) may enhance its effectiveness to treat hypokinetic gait in PD. Three-dimensional kinematic gait analysis was performed (1) prior to, (2) immediately after and (3) 30 min after low-frequency rTMS (1 Hz, 900 pulses, 80% of resting motor threshold) over M1 contralateral to the more affected body side preconditioned by (1) cathodal, (2) anodal or (3) sham tDCS (amperage: 1 mA, duration: 10 min) in ten subjects with PD (7 females, mean age 63 ± 9 years) and ten healthy subjects (four females, mean age 50 ± 11 years). The effects of tDCS-preconditioned rTMS on gait kinematics were assessed by the following parameters: number of steps, step length, stride length, double support time, cadence, swing and stance phases. Our data suggest a bilateral improvement of hypokinetic gait in PD after 1 Hz rTMS over M1 of the more affected body side preceded by anodal tDCS. In contrast, 1 Hz rTMS alone (preceded by sham tDCS) and 1 Hz rTMS preceded by cathodal tDCS were ineffective to improve gait kinematics in PD. In healthy subjects, gait kinematics was unaffected by either intervention. Preconditioning motor cortex rTMS by tDCS is a promising approach to treat hypokinetic gait in PD.

  2. The Event-Related Low-Frequency Activity of Highly and Average Intelligent Children

    ERIC Educational Resources Information Center

    Liu, Tongran; Shi, Jiannong; Zhao, Daheng; Yang, Jie

    2008-01-01

    Using time-frequency analysis techniques to investigate the event-related low-frequency (delta: 0.5-4 Hz; theta: 4-8 Hz) activity of auditory event-related potentials (ERPs) data of highly and average intelligent children, 18 intellectually gifted children, and 18 intellectually average children participated the present study. Present findings…

  3. Firing Frequency Maxima of Fast-Spiking Neurons in Human, Monkey, and Mouse Neocortex

    PubMed Central

    Wang, Bo; Ke, Wei; Guang, Jing; Chen, Guang; Yin, Luping; Deng, Suixin; He, Quansheng; Liu, Yaping; He, Ting; Zheng, Rui; Jiang, Yanbo; Zhang, Xiaoxue; Li, Tianfu; Luan, Guoming; Lu, Haidong D.; Zhang, Mingsha; Zhang, Xiaohui; Shu, Yousheng

    2016-01-01

    Cortical fast-spiking (FS) neurons generate high-frequency action potentials (APs) without apparent frequency accommodation, thus providing fast and precise inhibition. However, the maximal firing frequency that they can reach, particularly in primate neocortex, remains unclear. Here, by recording in human, monkey, and mouse neocortical slices, we revealed that FS neurons in human association cortices (mostly temporal) could generate APs at a maximal mean frequency (Fmean) of 338 Hz and a maximal instantaneous frequency (Finst) of 453 Hz, and they increase with age. The maximal firing frequency of FS neurons in the association cortices (frontal and temporal) of monkey was even higher (Fmean 450 Hz, Finst 611 Hz), whereas in the association cortex (entorhinal) of mouse it was much lower (Fmean 215 Hz, Finst 342 Hz). Moreover, FS neurons in mouse primary visual cortex (V1) could fire at higher frequencies (Fmean 415 Hz, Finst 582 Hz) than those in association cortex. We further validated our in vitro data by examining spikes of putative FS neurons in behaving monkey and mouse. Together, our results demonstrate that the maximal firing frequency of FS neurons varies between species and cortical areas. PMID:27803650

  4. Successful Treatment of Phantom Limb Pain by 1 Hz Repetitive Transcranial Magnetic Stimulation Over Affected Supplementary Motor Complex: A Case Report

    PubMed Central

    Lee, Jong-Hoo; Byun, Jeong-Hyun; Choe, Yu-Ri; Lim, Seung-Kyu; Lee, Ka-Young

    2015-01-01

    A 37-year-old man with a right transfemoral amputation suffered from severe phantom limb pain (PLP). After targeting the affected supplementary motor complex (SMC) or primary motor cortex (PMC) using a neuro-navigation system with 800 stimuli of 1 Hz repetitive transcranial magnetic stimulation (rTMS) at 85% of resting motor threshold, the 1 Hz rTMS over SMC dramatically reduced his visual analog scale (VAS) of PLP from 7 to 0. However, the 1 Hz rTMS over PMC failed to reduce pain. To our knowledge, this is the first case report of a successfully treated severe PLP with a low frequency rTMS over SMC in affected hemisphere. PMID:26361601

  5. Successful Treatment of Phantom Limb Pain by 1 Hz Repetitive Transcranial Magnetic Stimulation Over Affected Supplementary Motor Complex: A Case Report.

    PubMed

    Lee, Jong-Hoo; Byun, Jeong-Hyun; Choe, Yu-Ri; Lim, Seung-Kyu; Lee, Ka-Young; Choi, In-Sung

    2015-08-01

    A 37-year-old man with a right transfemoral amputation suffered from severe phantom limb pain (PLP). After targeting the affected supplementary motor complex (SMC) or primary motor cortex (PMC) using a neuro-navigation system with 800 stimuli of 1 Hz repetitive transcranial magnetic stimulation (rTMS) at 85% of resting motor threshold, the 1 Hz rTMS over SMC dramatically reduced his visual analog scale (VAS) of PLP from 7 to 0. However, the 1 Hz rTMS over PMC failed to reduce pain. To our knowledge, this is the first case report of a successfully treated severe PLP with a low frequency rTMS over SMC in affected hemisphere. PMID:26361601

  6. Timing jitter characterization of mode-locked lasers with <1 zs/√Hz resolution using a simple optical heterodyne technique.

    PubMed

    Hou, D; Lee, C-C; Yang, Z; Schibli, T R

    2015-07-01

    Timing jitter characterization of free-running mode-locked lasers with an unprecedented resolution is demonstrated using an optical heterodyne technique. A highly sensitive timing jitter phase-discrimination signal with low-parasitic-amplitude sensitivity is achieved. Analytical and numerical methods are used to analyze the properties of the discrimination signal. For an experimental demonstration, we measure the timing jitter between two loosely synchronized mode-locked Er:Yb:glass lasers with 500-MHz fundamental repetition rates. The timing jitter-detection noise floor for a single mode-locked laser reaches 2.8×10(-13)  fs(2)/Hz (∼530  ys/√Hz), and the integrated timing jitter is 16.3 as from 10 kHz to the Nyquist frequency (250 MHz). These results show that this approach can be a simpler alternative to the well-established balanced optical cross-correlation technique. PMID:26125348

  7. Nanohertz frequency determination for the gravity probe B high frequency superconducting quantum interference device signal.

    PubMed

    Salomon, M; Conklin, J W; Kozaczuk, J; Berberian, J E; Keiser, G M; Silbergleit, A S; Worden, P; Santiago, D I

    2011-12-01

    In this paper, we present a method to measure the frequency and the frequency change rate of a digital signal. This method consists of three consecutive algorithms: frequency interpolation, phase differencing, and a third algorithm specifically designed and tested by the authors. The succession of these three algorithms allowed a 5 parts in 10(10) resolution in frequency determination. The algorithm developed by the authors can be applied to a sampled scalar signal such that a model linking the harmonics of its main frequency to the underlying physical phenomenon is available. This method was developed in the framework of the gravity probe B (GP-B) mission. It was applied to the high frequency (HF) component of GP-B's superconducting quantum interference device signal, whose main frequency f(z) is close to the spin frequency of the gyroscopes used in the experiment. A 30 nHz resolution in signal frequency and a 0.1 pHz/s resolution in its decay rate were achieved out of a succession of 1.86 s-long stretches of signal sampled at 2200 Hz. This paper describes the underlying theory of the frequency measurement method as well as its application to GP-B's HF science signal.

  8. A frequency-addressed plasmonic switch based on dual-frequency liquid crystals

    NASA Astrophysics Data System (ADS)

    Liu, Yan Jun; Hao, Qingzhen; Smalley, Joseph S. T.; Liou, Justin; Khoo, Iam Choon; Huang, Tony Jun

    2010-08-01

    A frequency-addressed plasmonic switch was demonstrated by embedding a uniform gold nanodisk array into dual-frequency liquid crystals (DFLCs). The optical properties of the hybrid system were characterized by extinction spectra of localized surface plasmon resonances (LSPRs). The LSPR peak was tuned using a frequency-dependent electric field. A ˜4 nm blueshift was observed for frequencies below 15 kHz, and a 23 nm redshift was observed for frequencies above 15 kHz. The switching time for the system was ˜40 ms. This DFLC-based active plasmonic system demonstrates an excellent, reversible, frequency-dependent switching behavior and could be used in future integrated nanophotonic circuits.

  9. Robust frequency stabilization of multiple spectroscopy lasers with large and tunable offset frequencies.

    PubMed

    Nevsky, A; Alighanbari, S; Chen, Q-F; Ernsting, I; Vasilyev, S; Schiller, S; Barwood, G; Gill, P; Poli, N; Tino, G M

    2013-11-15

    We have demonstrated a compact, robust device for simultaneous absolute frequency stabilization of three diode lasers whose carrier frequencies can be chosen freely relative to the reference. A rigid ULE multicavity block is employed, and, for each laser, the sideband locking technique is applied. A small lock error, computer control of frequency offset, wide range of frequency offset, simple construction, and robust operation are the useful features of the system. One concrete application is as a stabilization unit for the cooling and trapping lasers of a neutral-atom lattice clock. The device significantly supports and improves the clock's operation. The laser with the most stringent requirements imposed by this application is stabilized to a line width of 70 Hz, and a residual frequency drift less than 0.5 Hz/s. The carrier optical frequency can be tuned over 350 MHz while in lock.

  10. Vibration of the human tympanic membrane measured with OCT in a range between 0.4 kHz and 6.4 kHz on an ex vivo sample

    NASA Astrophysics Data System (ADS)

    Burkhardt, Anke; Kirsten, Lars; Bornitz, Matthias; Zahnert, Thomas; Koch, Edmund

    2013-06-01

    Vibrations of the tympanic membrane (TM) play a key role for the transmission of sound to the inner ear. Today, there exist still problems in measuring the movement of the TM and there are unresolved issues in understanding the TM and its behavior. A non-invasive and contact-free in vivo investigation of the structure and the functional behavior of the TM would be a big step forward. In the presented study, the suitability of optical coherence tomography (OCT) for measuring the oscillation patterns of the TM in the frequency range covering the range of the human speech perception should be tested. For functional imaging a sound chirp was generated in the frequency range between 0.4 kHz - 6.4 kHz. To obtain the movement within a sufficient resolution, a grid of 25 x 25 measurement points was generated over the whole TM. The information of the oscillatory movement was encoded in the Doppler signal, provided by M-scans at several points of the TM. The frequency response functions of each frequency showed different oscillation patterns on the TM. The acquisition time of one single M-scan was only 8.5 ms and of the entire TM 5.3 s, emphasizing the potential of the method for future in vivo applications. Furthermore, the morphology was acquired with the same OCT-system, showing the feasibility for structural imaging and differentiation between typical regions of the TM. Thus, OCT was shown as a suitable method for the simultaneous measurement of the functional and structural behavior of the TM.

  11. Effects on atmospherics at 6 kHz and 9 kHz recorded at Tripura during the India-Pakistan Border earthquake

    NASA Astrophysics Data System (ADS)

    de, S. S.; de, B. K.; Bandyopadhyay, B.; Paul, S.; Haldar, D. K.; Bhowmick, A.; Barui, S.; Ali, R.

    2010-04-01

    The outcome of the results of some analyses of electromagnetic emissions recorded by VLF receivers at 6 kHz and 9 kHz over Agartala, Tripura, the North-Eastern state of India (Lat. 23° N, Long. 91.4° E) during the large earthquake at Muzaffarabad (Lat. 34.53° N, Long. 73.58° E) at Kashmir under Pakistan have been presented here. Spiky variations in integrated field intensity of atmospherics (IFIA) at 6 and 9 kHz have been observed 10 days prior (from midnight of 28 September 2005) to the day of occurrence of the earthquake on 8 October 2005 and the effect continued, decayed gradually and eventually ceased on 16 October 2005. The spikes distinctly superimposed on the ambient level with mutual separation of 2-5 min. Occurrence number of spikes per hour and total duration of their occurrence have been found remarkably high on the day of occurrence of the earthquake. The spike heights are higher at 6 kHz than at 9 kHz. The results have been explained on the basis of generation of electromagnetic radiation associated with fracture of rocks, their subsequent penetration into the Earth's atmosphere and finally their propagation between Earth-ionosphere waveguide. The present observation shows that VLF anomaly is well-confined between 6 and 9 kHz.

  12. 47 CFR 15.217 - Operation in the band 160-190 kHz.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 1 2011-10-01 2011-10-01 false Operation in the band 160-190 kHz. 15.217... Intentional Radiators Radiated Emission Limits, Additional Provisions § 15.217 Operation in the band 160-190 k... lead (if used) shall not exceed 15 meters. (c) All emissions below 160 kHz or above 190 kHz shall...

  13. 47 CFR 15.217 - Operation in the band 160-190 kHz.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 1 2013-10-01 2013-10-01 false Operation in the band 160-190 kHz. 15.217... Intentional Radiators Radiated Emission Limits, Additional Provisions § 15.217 Operation in the band 160-190 k... lead (if used) shall not exceed 15 meters. (c) All emissions below 160 kHz or above 190 kHz shall...

  14. 47 CFR 15.217 - Operation in the band 160-190 kHz.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 1 2014-10-01 2014-10-01 false Operation in the band 160-190 kHz. 15.217... Intentional Radiators Radiated Emission Limits, Additional Provisions § 15.217 Operation in the band 160-190 k... lead (if used) shall not exceed 15 meters. (c) All emissions below 160 kHz or above 190 kHz shall...

  15. 47 CFR 15.217 - Operation in the band 160-190 kHz.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 1 2012-10-01 2012-10-01 false Operation in the band 160-190 kHz. 15.217... Intentional Radiators Radiated Emission Limits, Additional Provisions § 15.217 Operation in the band 160-190 k... lead (if used) shall not exceed 15 meters. (c) All emissions below 160 kHz or above 190 kHz shall...

  16. 47 CFR 15.217 - Operation in the band 160-190 kHz.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false Operation in the band 160-190 kHz. 15.217... Intentional Radiators Radiated Emission Limits, Additional Provisions § 15.217 Operation in the band 160-190 k... lead (if used) shall not exceed 15 meters. (c) All emissions below 160 kHz or above 190 kHz shall...

  17. Real-Time, High-Frequency QRS Electrocardiograph

    NASA Technical Reports Server (NTRS)

    Schlegel, Todd T.; DePalma, Jude L.; Moradi, Saeed

    2003-01-01

    An electronic system that performs real-time analysis of the low-amplitude, high-frequency, ordinarily invisible components of the QRS portion of an electrocardiographic signal in real time has been developed. Whereas the signals readily visible on a conventional electrocardiogram (ECG) have amplitudes of the order of a millivolt and are characterized by frequencies <100 Hz, the ordinarily invisible components have amplitudes in the microvolt range and are characterized by frequencies from about 150 to about 250 Hz. Deviations of these high-frequency components from a normal pattern can be indicative of myocardial ischemia or myocardial infarction

  18. A MEMS-based high frequency x-ray chopper.

    PubMed

    Siria, A; Dhez, O; Schwartz, W; Torricelli, G; Comin, F; Chevrier, J

    2009-04-29

    Time-resolved x-ray experiments require intensity modulation at high frequencies (advanced rotating choppers have nowadays reached the kHz range). We here demonstrate that a silicon microlever oscillating at 13 kHz with nanometric amplitude can be used as a high frequency x-ray chopper. We claim that using micro-and nanoelectromechanical systems (MEMS and NEMS), it will be possible to achieve higher frequencies in excess of hundreds of megahertz. Working at such a frequency can open a wealth of possibilities in chemistry, biology and physics time-resolved experiments.

  19. Thermal Nondestructive Evaluation Report: Inspection of the Refurbished Manipulator Arm System in the Manipulator Development Facility at Johnson Space Center 10-12 January 2001

    NASA Technical Reports Server (NTRS)

    Cramer, K. Elliott

    2002-01-01

    On 4 December 2002, a failure of the Refurbished Manipulator Arm System (RMAS) occurred in the Manipulator Development Facility (MDF) at Johnson Space Center. When the Test Director commanded a should pitch maneuver to lift the arm from its payload bay pedestal, the yaw controls failed. This, coupled with a gravitational forces (due to the angle of the shoulder joint with respect to vertical), resulted in uncontrolled arm motion. The shoulder yaw joint moved approximately 20 degrees, causing the extended arm to strike and severely damage the port side MDF catwalk handrails. The arm motion stopped after impact with the handrails. On 10-12 January 2001, inspections were performed on the port face of the lower and upper arms of the RMAS using a infrared thermography developed at Langley Research Center. This paper presents the results of those nondestructive inspections and provides a complete description of the anomalies found and their locations.

  20. Statistical analysis of Stromboli VLP tremor in the band (0.1-0.5)Hz: Some consequences for geometrical vibrating structure

    NASA Astrophysics Data System (ADS)

    Palo, M.; de Lauro, E.; de Martino, S.; Falanga, M.

    2006-12-01

    We analyze time series of strombolian volcanic tremor recorded during the experiment performed in 1997 by using 21 three-component broadband seismometers. This work is devoted to the careful analysis of the frequency band [0.1-0.5] Hz in order to obtain information about the properties of volcanic tremor and the microseismic noise. In fact, although this frequency band is largely affected by noise, we infer the possibility of simpler hidden structures. We evidence two significant components by using Independent Component Analysis with the frequencies, respectively, of about 0.2 and 0.4 Hz. We show that these components display wavefield features similar to those of the high frequency strombolian signals (greater than 0.5 Hz). In fact they are radially polarised and located within the crater area. This characterization is lost when an enhancement of energy appears. In this case the presence of microseismic noise becomes relevant. Investigating the entire large data- set available, we determine how microseismic noise influences the signals. We ascribed the microseismic noise source to Scirocco wind. Moreover, our analysis allows one to affirm that the strombolian conduit vibrates like the asymmetric cavity associated with musical instruments generating self-sustained tones.